Windows movie maker

Hello....I have an older computer that runs on XP. It is not hooked to internet. I use it to put home movies into movie maker. I went to play a file, and it loaded up with large red xs all thru it. i can hit play and the curser will start moving, just like it was playing the move, but nothing shows up. Says the file can't be found, but its playing the file, just not visiable. Large red Xs. This happened before and i took it to a friend. He did all sorts of things and finally the Xs were gone, and it was working. Bad part is he doesn't know what he did to fix it. When it appears to be playing across these Xs, when it gets to the end of the clips, it stops, just as it should. Would appreciate any help as what to do. Maybe some setting needs changed somewhere. HELP........Dan       *** Email address is removed for privacy ***