To be honest, the LW/FW player is horrible so you're better off using another player anyway

But if you're desperate to use the built in player, try this: Delete 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 kill 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 (just substitute FW for LW here...I'm not going to edit the whole thing)