Try deleting LW's preferences folder when LW's properly closed. See point 3 here.
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. And in case you're using Vista...LimeWire Pref Folder in Vista

Which version of Java are you using? Some people have had trouble with the latest Java updates. Try this version instead. Use the JRE offline installer & remove your current Java version before installing this one (it's easy enough to reinstall a later Java if it turns out that Java's the problem).
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

If that doesn't help, try reinstalling the latest version of LW (4.14.8) & make sure to use the offline installer (when you click to download LW & the download box pops up, cancel that & you'll see the option to use the offline installer).
Lime Wire » Download LimeWire

If all that fails, right click on the LW desktop icon > properties > compatibility & run in compatibility mode for Win 2000 or NT, if you're using Win XP. If you're using Vista, try compatibility mode for XP.