That's odd. I would still recommend VLC. I use VLC for some video types & QuickTime for one or 2 other video formats as the default in OSX.

Perhaps try deleting LW preferences whilst LW is CLOSED. You'll find it here: /Users/your_username/Library/Preferences/LimeWire

Tell us if it makes any difference.

Also, it might be worth doing this SAFE Boot & Repair Permissions As this is generally recommended after installing new software or system updates.

BTW what do you use to preview audio files with? VLC can also play most audio formats even though it's fundamentally a video program; http://www.videolan.org/vlc/features.html
I use VLC for most of my audio streaming (occasionally use iTunes.)