Are you using the LW player? If so, try using a different one. LW's player tends to skip, pop, and generally mess up, especially if your using your computer for other things while your playing files.
Open LW and go to Tools>Options>Player, untick the box by "Use LimeWire Media Player" > Apply > OK. Your songs will now launch in your default player.
I use
winamp but there are plenty of others out there. A good backup player is
VLC media player, it has the codecs built in and will play most file types.
CODECs list for Movies/Alternate players / Video help forums/ video-mp3 fixers How to set the Default applications
It could also be corrupt/fake files. See:
Fake files showing up in search results
Also:
Problems with the search How to find music(and video)