# Computer stuck at black screen with flashing white underscore



## IzalithFuror (Oct 22, 2012)

Today I started up my pc and after the BIOS screen (the place where you can press f8-f11 for various options) it went to a black screen with a blinking underscore in the upper left corner and stayed there indefinitely. It did this even after reboot. 

I tried using the diagnostic tool and everything it tested passed (including HDD). I did this test twice and the same results were produced.

I also googled for similar problems (one topic mentioned that the op disassembling his computer and physically tapping a chip on the motherboard caused it to work) but I have no experience with taking apart my computer and i do not want to break it accidentally. I did however chance upon a topic advising him to do a CMOS reset which apparently helped that op, so i looked through the various options on the BIOS page. There was one option (f10 I think) mentioning CMOS on its fourth sub-window, so i pressed the reset option but I'm not entirely sure if I used the right function.

I uninstalled kaspersky pure and replaced kaspersky pure for kaspersky anti-virus yesterday, dont know if this was the cause.

I am using windows 7 64 bit. *However, I am also not able to tell whether it is Windows 7 Home Premium, Pro or Ultimate because I have no idea how to access to the start menu or the run dialog from what amounts to basically only the BIOS screen. As such I cannot tell which is the proper windows 7 SP1 ISO that I should be using. Can anyone help? *


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## joeten (Dec 4, 2008)

Hi and welcome to TSF please post the make and model of your computer or if a custom build the make and model of 
Motherboard
cpu
gpu
ram
psu


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## shawnpb (May 30, 2010)

Reboot or turn on the machine. As soon as you see your machine's name logo splash screen keep tapping *F8*. Go to *"Advanced Options"* or *"Repair Computer" *Select your language then *"Repair Your Computer"* An installation of Windows should be detected after that select *"Next"* 

If that does not fix the issue. Do the same as before go to Next again go to command prompt type in 

```
CHKDSK C: /R
```


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## IzalithFuror (Oct 22, 2012)

The only splash logo I can get to is this one:










I spammed F8, it showed another screen that was too fast to see. After that it instantly skipped to the black screen with flashing underscore.


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## Riskyone101 (Oct 22, 2008)

Yes, replacing kaspersky pure for kaspersky anti-virus is probably what caused the windows to get corrupted with spyware.

Kaspersky pure is a full suite while as kaspersky anti-virus is only antivirus program
no antispyware protection.


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## IzalithFuror (Oct 22, 2012)

Sorry, I meant Kaspersky internet security. Says on the box it has anti-spyware too. The shop told me they were phasing pure out.


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## Riskyone101 (Oct 22, 2008)

joeten said:


> Hi and welcome to TSF please post the make and model of your computer or if a custom build the make and model of
> Motherboard
> cpu
> gpu
> ...


Laptop?..make and model number please.


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## AustrAlien (Jun 10, 2009)

IzalithFuror said:


> ... a black screen with a blinking underscore in the upper left corner ...


It is likely that the MBR (Master Boot Record) is damaged/corrupt. Let's have a look at it:

You will need a USB drive/flashdrive and a new blank writable CD.
Step 1: *Please do the following on a working computer:*

Download *GETxPUD.exe* to the Desktop.
Run *GETxPUD.exe*
A new folder will appear on the desktop.
Open the *GETxPUD* folder and click on *get&burn.bat*
The program will download *xpud_0.9.2.iso*, and when finished will open *BurnCDCC* ready to burn the image.
_Please be patient: This could take awhile - download file size 63MB._
Click on *Start* and follow the prompts to burn the image to a CD.
*You will use this CD to boot the ailing computer from.*


Step 2: *Boot the ailing computer with the xPUD CD.*


_(You may have to configure the Boot Menu or BIOS Setup Menu to boot first from the optical/CD/DVD drive.)_
A *Welcome to xPUD* screen will appear.
Click on *File*.
Expand the *mnt* icon on the left _(click on the little arrow beside the icon)_.
sda1, sda2 etc. ...usually correspond to your HDD partitions
sdb1, sdc1 is likely to correspond to a USB flashdrive, external USB hard drive etc.

Click on the folder that represents your USB drive (sdb1 ?).
Click *Tool* on the top menu, and choose *Open Terminal*.
Type the following at the hash prompt:

*dd if=/dev/sda of=mbr.bin bs=512 count=1*


*Note: Leave a space between the following:*
*dd* ... the executable application used to create the backup
*if=/dev/sda* ... the device the backup is created from (the hard drive when only one HDD exists)
*of=mbr.bin* ... the backup file to create - note the lack of a path - it will be created in the directory currently open in the Terminal
*bs=512* ... the number of bytes in the backup
*count=1* ... says to backup just 1 sector
*It is extremely important that the if and of statements are correctly entered.*


Press the <ENTER> key.
After it has finished a file will be located on your USB drive named *mbr.bin*.
Go to *Home* > *Power Off* > *Turn Off* and remove the flashdrive as the system shuts down.

Step 3: *On the working computer:*

Insert the USB drive, and navigate to the file *mbr.bin*
Zip-up the *mbr.bin* file:
Right-click on the file and choose *Send to ..* > *Compressed (zipped) Folder*.
A zipped folder will appear in the same location as the mbr.bin file.

Please *attach* the zipped file to your next reply.
This will allow the MasterBootRecord of your hard drive to be checked to see whether or not it is infected &/or damaged.


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## IzalithFuror (Oct 22, 2012)

Riskyone101 said:


> Laptop?..make and model number please.


From the side of the computer

HP pavilion p6298d Home PC

intel core i5 processor i5-750
6144MB DDR3
1000gb 3G hard drive
NVIDIA Geforce GT230
Supermulti drive with lightscribe technology

From the f9 diagnosis screen:
Intel core i5 processor i5-750 @2.67 GHz
Memory (6144 MB)
Hitachi HDT721010SLA360 drive
Hp dvd-ram GH40L

Sadly that's all I managed to find so far, is it enough?

Also, my computer has no external buttons with which to eject the cd or dvd drive. So I am afraid I cannot boot from CD, can I boot from flash drive instead?


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## AustrAlien (Jun 10, 2009)

IzalithFuror said:


> ... can I boot from flash drive instead?


If your computer is able to boot from a flashdrive, here are the instructions ...

You will need a USB hard drive or flashdrive.

Step 1: Download http://unetbootin.sourceforge.net/unetbootin-xpud-windows-latest.exe
and http://noahdfear.net/downloads/bootable/xPUD/xpud-0.9.2.iso to the desktop of a working computer:

Insert a USB flashdrive.
Go to *Start* > *My Computer* > right-click on the flashdrive > choose *Format* > *Quick format*.
Double-click the *unetbootin-xpud-windows-387.exe* that you just downloaded.
Click *Run* > *OK*.
Select the *DiskImage* option and then click the browse button located on the right side of the text-box field.
Browse to and select the *xpud-0.9.2.iso* file that you downloaded.
Verify the correct drive letter is selected for your flashdrive, and then click *OK*.
A small bootable Linux operating system will be installed on the flashdrive.
Once the files have been written to the device, you will be prompted to reboot: Do not reboot the computer.
Instead, just exit the UNetbootin interface (simply close the installer).

Remove the flashdrive from the computer.
*You will use this flashdrive to boot the ailing computer from.*


Step 2: *Boot the ailing computer with the xPUD flashdrive.*


_(You may have to configure the Boot Menu or BIOS Setup Menu to boot first from the flashdrive/USB HDD.)_
A *Welcome to xPUD* screen will appear.
Click on *File*.
Expand the *mnt* icon on the left _(click on the little arrow beside the icon)_.
sda1, sda2 etc. ...usually correspond to your HDD partitions
sdb1, sdc1 is likely to correspond to a USB flashdrive, external USB hard drive etc.
_*Note:* It may happen that after booting to xPUD on a flashdrive and then looking for the flashdrive, you are not able to find it anywhere. *If this happens, simply unplug the flashdrive, wait briefly and then re-plug it back into the system*, and it should now show up._

Click on the folder that represents your USB drive (sdb1 ?).
Click *Tool* on the top menu, and choose *Open Terminal*.
Type the following at the hash prompt:

*dd if=/dev/sda of=mbr.bin bs=512 count=1*


*Note: Leave a space between the following:*
*dd* ... the executable application used to create the backup
*if=/dev/sda* ... the device the backup is created from (the hard drive when only one HDD exists)
*of=mbr.bin* ... the backup file to create - note the lack of a path - it will be created in the directory currently open in the Terminal
*bs=512* ... the number of bytes in the backup
*count=1* ... says to backup just 1 sector
*It is extremely important that the if and of statements are correctly entered.*


Press the <ENTER> key.
After it has finished a file will be located on your USB drive named *mbr.bin*.
Go to *Home* > *Power Off* > *Turn Off* and remove the flashdrive as the system shuts down.

Step 3: *On the working computer:*

Insert the flashdrive, and navigate to the file *mbr.bin*
Zip-up the *mbr.bin* file:
Right-click on the file and choose *Send to ..* > *Compressed (zipped) Folder*.
A zipped folder will appear in the same location as the mbr.bin file.

Please *attach* the zipped file to your next reply.
This will allow the MasterBootRecord of your hard drive to be checked to see whether or not it is infected &/or damaged.


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## Riskyone101 (Oct 22, 2008)

Power supply unit - name and wattage?


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## IzalithFuror (Oct 22, 2012)

It's a desktop, I'm not sure how to check that. ><


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## joeten (Dec 4, 2008)

the side of the computer tower will either slide off or you undo a couple of screws usually if your looking at the tower face on it would be the right side from the rear the left screws are normally top and bottom once the side is off you can see the psu label with the name and wattage


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## Riskyone101 (Oct 22, 2008)

They give illustrations here:
How To Replace Your Power Supply | Hardware Secrets


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## IzalithFuror (Oct 22, 2012)

OHH MY SWEET JESUS, I KNOW WHY MY COMPUTER REFUSED TO BOOT

The f9 diagnostics test said my desktop computer's HDD was perfectly fine, so I took it out and put it in an enclosure to check it to try and extract data from what was inside. Everything was still intact so I suspected it was okay. 

I tried configuring it to boot from unetbootin and I realised the boot order had been set to 'CD' first. For whatever reason it was trying to boot from the Kaspersky internet security installation CD I had left inside. Computer is running again now that I put HDD as first priority in boot order. 

Apparently something in Kaspersky was recognized by the computer as a bootable OS, and it was trying to boot from Kaspersky the whole damn time (and thus showing a blinking white underscore).

Oh yeah, the side of the computer says it is an
AC input 100-127V -6A 
50/60 Hz 200-240V - 3A
power supply.

1) By the way, now that my computer is working again, how do I duplicate my data in the case that my computer actually does fail? I've backed up before, but it only seems to back up a limited number/section of files. Iirc it didn't backup the things on the desktop, which is where I put a load of important files.

2) While I was running the master boot log thing using the Unetbootin USB, I realised that the posted instructions said to select the USB drive and get the log from there. Wouldn't the point be to get the log from the HDD so as to identify problems in the HDD, since the HDD is the one with the error?


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## joeten (Dec 4, 2008)

LOL we should have thought of that is it a back up or full image your looking to do


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## IzalithFuror (Oct 22, 2012)

joeten said:


> LOL we should have thought of that is it a back up or full image your looking to do


What's the difference between the two?


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## joeten (Dec 4, 2008)

This should help explain Imaging Software vs. Backup Software- Which is Right for You? - TopTenREVIEWS


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## IzalithFuror (Oct 22, 2012)

Ah, thanks, I'm looking to do a full image. What do I need to have on hand/how do I go about it?


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## joeten (Dec 4, 2008)

If you use a paid for program then acronis Backup software for data backup and recovery | Acronis
for free ones see here for suggestions Best Free Drive Imaging Program


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