iTunes 7 - crashes when playing video, no video sound

I updated iTunes and Quicktime and now:
- iTunes crashes whenever I try to play a video I purchased.
- No sound in iTunes when playing my own video clips, podcast video clips etc.
- No sound with Quicktime movies in Safari.
- But can play any video from Quicktime and Front Row - sound works fine.

Tried reinstalling both the latest version of Quicktime (7.1.3) and an older version (let me just say very bad things happened).
Also checked the Audio Output setting and it is at 44100.0 Hz..

??!!

Using Intel Mac OS 10.4.7

Applematters reports many having problems..

with iTunes 7. I have not experienced any problems that I know of and I have downloaded album art, etc. but many people are reporting all sorts of problems. Some have even lost music files.

sounds like Apple needed to do some more testing b4 this version came out