won't play past projects mulitple error msgs

I'm so confused. Maybe another downloaded program
corrupted the MM2, but it's baffled me to no end.

My clips won't play for several reasons. ClassFile
error, or that was the previous msg I got before now it
doesn't play at all. It just clicks on the clip, or in
the timeline and nothing. As if there is no audio so
nothing is being performed in the playback.

What I'd like to do is UnInstall MM2 or just MM itself
and start from scratch. Granted I'll lose all my
imported video and audio, but I'd rather do that then
pull my hair out. HELP, please.