Windows 7 - Having issues playing divx/xvid avi/mkv files all the sudden

I have windows 7 32 bit. I've been watching avi and mkv files encodes in dixv and xvid for years now. All the sudden tonight when I go to click on one, it just says it can't play the in file windows media player. When I tried it in the KM player, it just froze. Tried with various other avi files i have and did the same thing, so I know its not just the file. I went to go and reinstall Divx codec and for whatever bizarre reason, when I have my documents folder open that the files are located in, windows explorer crashes and has to restart. If I open my documents again, it does the same thing. When I uninstall Divx, the problem is gone. All I wanna do is watch my damn avi episodes, this should not be such a headache!