They're probably fakes:
Fake files showing up in search results
If your using LW's player, shut it off and use 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.
How to find music(and video)