Ahh, I lost track of this thread! I did not (and cannot) format/reinstall Windows, I don't see why that should be necessary. WMP11 was upgraded to. I recently upgraded QuickTime but the problem only occurred when I upgraded to WMP11, which wasn't at the same time, but I don't remember whether it was before or after. I have 1GB
RAM. I know my AVIs are not corrupted as most of the ones I'm trying to play are ones I've played successfully before the upgrade.
I don't know where to go to upgrade codecs...