There are several things that I can see that might be driving your mp3 player haywire:
A) About 1/3 of Limewire songs contained some type of writing in the "Comments" section of the songs' ID3 Tags before version 5 - it may be up to 100% now, and your player obviously doesn't like it. This is going to be a real bear, but I would take one of the songs you just downloaded, open it in Windows Media Player, and right-click the song title within Windows Media Player. Select "Advanced Tag Editor," and delete any writing that appears in the "Comments" section of the ID3 tag. Then try transferring that song to your player and see if it plays correctly. If it does, repeat with all of the songs you just downloaded. It will take you forever.
B) If you use iTunes to transfer songs to your mp3 player, version 5 will not work with iTunes - it simply pastes a data file into iTunes which is not the actual song, so it may appear to transfer correctly, but in fact you have not transferred the actual song file. Use Windows Media Player to transfer instead.
C) The bitrate on songs in version 5 is higher - most mp3 players have a maximum bit rate that they can handle, and ver. 5 might exceed this upper limit. The solution would be to convert all of your mp3 files to a lower bit rate using free software
such as Media Monkey.
Without dragging this explanation out any longer, I think your best solution would be to revert back to Ver. 4.1 or so.
-Tha Mp3 Doctor