Maybe a codec problem. Try using
VLC Media Player, it has the codecs built in and can play most files. Or try d/ling another codec pack I see
K-Litecode Codec Pack recommended alot.
More info in this thread:
CODECs list for Movies/Alternate players
If it sounds like it's playing too fast(like chipmunks), see this thread:
http://www.gnutellaforums.com/showth...353#post166353