Hi,

The two most common causes for this error are faulty memory (RAM)
and overheating do to dirty or inoperative cooling fans.

The most accurate way of testing memory modules is to have them tested
on a memory tester. In my experience I have found software testers to be
inaccurate.

Try switching RAM sticks if there is more than one
Use one stick, then another.  Only one at a time, of course.
If both sticks work alone but will not work when combined, that almost
certainly indicates an incompatibility between the two sticks.
If one stick works but the other does not, then that would indicate the one
that doesn't work is either faulty, will not get along with the other stick,
or
is not the correct type for your system.

Tip: While the box is open check to make sure all fans are clean and
operating.
     This will help eliminate the possibility of overheating.

Another possible cause:
Registry scanner finds corrupted files and restores from a backup, and then
gets caught in a continual loop after installing Norton AntiVirus 2001
http://snipurl.com/10w

Registry Checker Continues to Detect Registry Damage
http://support.microsoft.com/support/kb/articles/q186/9/09.asp

There have also been reports of MSN Messenger causing this.
Uninstall Messenger to troubleshoot.

The Windows Cab files may be located on the hard drive.
Click start/find/files, search for win98*.cab. You may find them
in a folder like C:\Windows\options\cabs.