It could be an empty file. See: Fake files showing up in search results, How to find music(and movies).

It might be a codec problem. For Vista try: Vista Codec Package v4.4.5 (freeware)

Also try VLC media player, it has the codecs built in and is very reliable. If it plays in VLC then you know it was a codec problem.

More info: CODECs list for Movies/Alternate players / Video help forums/ video-mp3 fixers

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