WOW!
I was totally wrong.
That particular AMD model max temp is listed at 90C:
http://www.cpu-world.com/CPUs/K7/AMD-Athlon%20XP%202000%2B%20-%20AXDC2000DUT3C.htmlSo, I guess, you're OK there.
Oh boy, where do we go from here?
You tested RAM already with memtest, but....
If you have more than one RAM stick, try to run the computer for a day, or so, on one stick at a time.
With your variety of errors, it may be number of things.
Go Start>Run ("Start Search" in Vista/7), type in:
sfc /scannowClick OK (hold CTRL, and SHIFT, hit Enter in Vista/7).
Have Windows CD/DVD handy (with Vista/7, most likely, you won't need it).
If
System File Checker (sfc) will find any errors, it may ask you for the CD/DVD (rarely in Vista/7 case).
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Another thing to check....
Run hard drive diagnostics:
http://www.tacktech.com/display.cfm?ttid=287 (or
http://www.bleepingcomputer.com/forums/index.php?showtopic=28744&hl=hard+drive+diagnostic)
Make sure, you select tool, which is appropriate for the brand of your hard drive.
Depending on the program, it'll create bootable floppy, or bootable CD.
If downloaded file is of
.iso type, use
ImgBurn:
http://www.imgburn.com/ to burn
.iso file to a CD (select "Write image file to disc" option), and make the CD bootable.
NOTE. If your hard drive is made by Toshiba, unfortunately, you're out of luck, because Toshiba doesn't provide any diagnostic tool.
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Also, try to reinstall your video driver.
The very last, but not least possibility, could be some infection.
