very curious problem...
 

im running limewire on osx.
program starts, connects, searches and downloads just fine.
when i try to preview the file in limewire, nothing happens.
i try to play the file in itunes, the length of the song comes up as something like 20 minutes (when i know its not) and there is no music.
and ive downloaded the same song 50 times to make sure it wasnt a corrupt file...
ive searched the forums but cant seem to find anyone with the same problem..please help!!! thanks in advance!!

Those 20 minute empty files are are spam/fake, put on the network to disrupt file sharing. There are a lot of them so it could be quite possible to download 50 fake files. More info on that subject here: Recognising Fake files.

Tips for finding good files here: How to find music.

Also the limewire player isn't very good and is prone to skipping and cutting out, so try playing files in another player before you scrap them;).