Edit video using Quicktime Pro?

Does anyone know something about Quicktime Pro? Here's my problem: I'm trying to use Quicktime Pro to cut out unnecessary bits from an AVI video. When I save the edited video, Quicktime converts it to a .MOV file. When I play back the file, there is only audio. The video is just a solid green screen. I tried exporting the file to .AVI and -mpeg4, and each time there is no video - only that green screen. What am I doing wrong?