# "stop c0000221 unknown hard error systemroot\system32\ntdll.dll"



## Khalidirfan (Dec 23, 2005)

"stop c0000221 unknown hard error systemroot\system32\ntdll.dll" while trying to install windows xp


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## whodat (Mar 13, 2005)

most likely a bad ram module or to aggressive timings

but first do a complete error check on the disk along with a virus/spy scan

read *this*

post back with the results


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## ikatanda (Nov 8, 2008)

Most probably a bad or missing ntdll file. Simply download a new ntdll version and problem solved! Read : http://www.pcnirvana.net/registry_error_ntdll_dll.html


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## ThorXP (Mar 11, 2008)

How to troubleshoot a "STOP 0xC000021A" error

http://support.microsoft.com/default.aspx?scid=kb;en-us;156669


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## piercedsphynx (Apr 27, 2009)

I noticed a solution still hasn't been posted for this problem. This can be caused by a number of things but usually A) Bad XP CD. B) Bad HD C) Hardware conflict. If you can rule out A or B, then it must be C. To resolve a hardware conflict, you can try disabling UltraDMA for the CD-ROM/CDRW Drive in the computer's system bios setup, usually found under Advanced Chipset settings, for the IDE interface, for whatever channel the CD Drive is on (i.e. Primary Slave or Secondary Master... that worked for me) and if that does not work the drive itself might need to be replaced, or it could be another culprit such as the RAM. Good luck!


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