The LW player is really horrible & doesn't perform very well

If I were you, I'd disable the player (tools > options > player) & make something else your default player.

If you really do want to keep using the LW player, then try deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will change all of your settings within options, you'll have to go back through afterwards & reset things. If you're not sure of your settings, go through LW's tools > options & write them all down, so that you can reset things later.
LimeWire Pref Folder in Vista