You might try this:

http://windowsxp.mvps.org/IEFIX.htm

Then this:

http://cexx.org/lspfix.htm

No, by now I know that this problem is not a hardware problem
...........how do you "know".........what have you done to verify this?

Try these:

http://www.memtest86.com/
http://www.mersenne.org/freesoft.htm

The last one will really stress your memory and processor. Both need to run for at least an hour

Now get this, boot into safe mode and run it.

http://www.filehippo.com/download_ccleaner/

Run the disk check and defrag.

If that doesn't work, the next step is to disable as much as possible from startup and see if that fixes the problem. Gradually reintroduce things until you find the culprit.

Incidentally, what are your hardware specs?