Yeah, some people say something about conflicting codecs in that pack.
Try videolan's VLC player. Should play most (if not all) of your avis and it's multi-platform software (and free).

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

"Raise your can of Beer on high
And seal your fate forever
Our best years have passed us by
The Golden Age Of Leather"
-Blue Öyster Cult-