Since yesterday, I can't play any .AVI files. I haven't installed anything new on my system that could have caused this. When the video files are displayed as thumbnails, the first frame is displayed but when I try to play it (using Realplayer, Windows Media Player etc.) I just get a black screen, no sound and the position bar or timer doesn't move. In other words - Nothing! Mpegs and all the rest play fine.
Sounds like maybe a codec got corrupted. Drop files on AviCodec program. See if the video codec says "unsupported". If so, go to www.free-codecs.com and download what you need.
*Update* I've installed loads of .avi codecs and they still don't work. Anyway, I don't think it's a codec problem because you usually get an error message when that happens and all I get is a black video screen. Also I've tried converting the .avi files into .mpegs and the encoders can't read anything either. That is they create an .mpeg file but it's blank too. This is driving me clucking banannas people. If anyone can help out I'll owe you a life debt! Pleeeeease!
Try some of the .avi files on another PC. First thing is to find out if the files are bad or something is keeping just your PC from playing them.