I'm running Windows 7 Pro and added a new external USB drive. I move some avi files over to the drive and now they won't play when I try to play them using Windows Media Player. If I copy an avi file back to my C drive then the video will play. I can eliminate missing codecs as the problem since it will play if I copy it back to the original drive. If I copy it to a different directory on the same drive it will play fine as well. It will also play fine using media player classic. I did change the permissions on the folder where I am having problems playing the avi file. Does Windows Media Player require some specific privileges in order to play avi files? The error message I get is "Windows Media Player encountered a problem while trying to play the file."