windows xp professional continously crashing

i have had to reinstall xp almost every other week over the last 6 months. I normally get two types of errors. either-

1) Missing or Corrupt file at c:\windows\system32\config\system ...

or

2) windows could not start successfully....
on clicking start windows normally or last known configuration...its goes
to a blue screen and restarts.

also i am unable to format my drive using ntfs file system...therefore i format it using the ntfs quick format.

please let me know if you have any solution to this problem?