Tufenuf: I sure thank you a whole lot. I've been hassling with this for a long time, Disk Cleanup freezing on the first scanning box. I found and tried some fixes I found on google, that I really didn't understand (creating a regedit file, etc.) and also, tried "free" scans that would then make you buy a product to do the fixes.
I just used the link you posted and your instructions...and voila! For the first time in ages I was able to do a Disk Cleanup. (I have 2000, not XP, by the way.) CNET is cool -- now I feel like, why try anyplace else first? And you people who freely help other people are awesome. Thanks so much.