I've got deja vu and memory loss.
I know I've forgotten things before......
OK, being serious for a change. This happened to me a while back on one of the 98 machines. The /WINDOWS/TEMP folder was crammed with gazillions of mysterious files that all seemed to have something to do with ZIP files. Eventually realised that my viruscanner (McAfee) was unpacking zipped files to scan 'em and omitting to delete them afterwards. I took to purging my TEMP folder regularly for a while and then, in the strange way that things happen on M$ OSes, one day it stopped. Maybe the scan engine updated or Windows got it's wits back.
I've learned to ignore irritating but harmless glitches rather than take precipitate action or waste hours trying to track them down because they often rectify themselves after a bit.