Craig
I'll try to reinstall QT 7.3 and see if that helps any. I have 7.4.0 installed. You never know...

If you have Time Machine working, I've read (on the link below) that you can use that to go back to 7.3, though I honestly wouldn't know exactly what to keep or throw away.

More info on 7.3 vs. 7.4 here:

http://arstechnica.com/journals/apple.ars/2008/01/23/video-pros-dont-install-that-quicktime-7-4-update-yet