What error & code are you seeing??

First thing to try is deleting LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used much 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.

Have you updated your Java since LW was working? What version of Java are you using?