Files depicted as blank sheets just indicate that there is no default application set to play them. In that case, you have to set the application yourself by Ctrl-clicking the file in the Finder, clicking Get Info and setting the Open with with whatever application can open the files you want.
Also, there are posts in these formus saying something about files being depicted as blank sheets because their file names are too long (and, as a possible consequence, the file extension is truncated).

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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-