Try reinstalling your Java. Use the JRE offline installer & remove your current Java version before reinstalling.
Java SE Downloads

If that Java version's not good then try this one. Same deal with using the JRE offline installer & uninstalling the current version before reinstalling this one.
Java SE Downloads - Previous Release - JDK 5

If that doesn't help, delete 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). Check out the second blue link below for how to show hidden files & folders within Vista.
Fixes for LimeWire
LimeWire Pref Folder in Vista
This will kill all of your settings within options, you'll have to go back through afterwards & reset things.

If that's no help, try changing compatibility (point 5 in the 'fixes' thread). Try changing to XP or Win 2000.

If it's still not opening, let us know what antispyware/security programs you're using.