I usually use VirtualDub to take screenshots. But I wanted to try Quicktime Pro. With virtualDub, the files open without any problem. I tried with several avi files, and they all stop at 3:43 minutes in the quicktime time line. These movies are all longer than 3:43.
And apparently, I'm not the only one having this problem
check this out
http://www.wwug.com/forums/apple_qui....htm#startloop