Which version of LW & Java are you using? Are you having issues like this with any other program?

First of all, update your Java (or reinstall if you're already using the latest Java): Java SE Downloads
Download the JRE offline installer & remove any other Java versions before installing a new one.
Reboot your computer after installing

If that doesn't help, 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.
In case you're using Vista: LimeWire Pref Folder in Vista