Mike,
I recently had this same problem. I registered here so that I could hopefully give you good news. I realize it’s been a while since your last post and you might have already fixed your problem. If so, then maybe this will help others. Go to your QuickTime installation directory and find QTCF.dll. Copy that file to \Adobe After Effects CS3\Support Files. Next time you start AE it should work.
Good Luck!
A