I recently installed the After Effects CS3 trial, so try my hand at motion tyop/motion typography.
When I first started the program, I tried to import one of my songs that's an MP3, after doing a google search, I found out that I had to first convert it to a .wav file before importing it. I downloaded audacity and converted the song I was going to try this with to a .wav file, opened After Effects CS3 again, and tried importing the newly converted .wav file, but yet again, After Effects crashes. I tried importing pictures as well, and those make it crash too.
Clean out the media cache using the purge functions in the Edit menu and the prefs. If that isn't sufficient, delete the prefs entirely (C:\Documents and Settings\Joe\Application Data\Adobe\after Effects\8.0\After Effects CS3 Prefs.txt). Also look into your OpenGL configuration. It may be necessary to disable it to prevent crashes due to incompatible hardware or drivers.