I just got a new computer that's running Windows 7. Previously I used XP, and had no problems (well, no unsolveable problems anyway!) with my Windows Movie Maker. Now I've transferred all my files to the new laptop, and just discovered when I went in to edit a video that I can't! That is, when I try to, the preview screen is blank although the audio for my video clips still plays. When I play the clips directly out of the "collections" folder, they play properly; it's only once I drag the clips into the timeline (or storyboard) to edit them that the screen goes blank. This is a problem I haven't seen before, and I couldn't find anyone else suffering from the same thing -- not footage that plays in one place, but not in the other. This is true of both movie files I created on the old computer and new files that I tried to create on this one (in case the problem was just a compatibility-across-OSs-thing). They're all in .wmv format. Any assistance would be greatly appreciated, thank you!

P.S. I have a 64-bit computer if that affects anything.

ETA: The screen is blank in fullscreen preview mode, too -- but again, only when playing from the timeline or storyboard. I can preview the clips in the "collections" folder just fine, even in fullscreen.