Swapfile: Control panel, System, Advanced options, Performance (on Win2k). Also known as virtual memory, it's disk space that gets used like memory. Swapping in and out of it is bad... SEt the initial size and max size to the same thing, and you have fixed swap space.
You might also consider reinstalling Windows over the existing installation. That may correct any bad DLLs or other files which could be causing grief. It's also a less stressful option than completely reinstalling the hard drive.
Also, consider doing a full scandisk. Switch your virtual memory around to a smaller size (but don't get rid of it!) and be sure to scan the entire drive, including a low-level scan.
And from Simmtester.com, you can get a memory testing program for free which will do some in-depth checking of your memory, and can help clue you in as to whether it's bad or not. Of course, if you can't run any programs, that won't help much...
