Unable to play some downloaded .mp3/Aiff

[cldjr]

Lately, some music files (.mp3/.AIFF) doesn't downloaded (?) as they should with LimeWire 4.18.3 Pro on iMac G4 OS X 10.4.11.
The download seems to go well into iTunes Music library but they doesn't appear in iTunes 7.7.1. (Limewire folder or/and main Library)
Double click on them in the iTunes Music Library to force to play, doesn't work.
QuickTime or RealPlayer are not able to open/play them.
Opening the file into Sound Studio 2.1 show an empty xxMb file.
... A new kind of Junk ?... Do I miss something ?
BTW, this is not happen to all downloaded music file...