I would uninstall LimeWire then do as LotR suggests. Run ad-aware, spybot, anti-virus, and a registry cleaner. Then do disk cleanup and disk deframentor.

By uninstalling LimeWire 1st you are removing any links that have been created to LimeWire causing your problem. This will make it easier for the programs mentioned above to find. This was probably caused by some other malicious program or a registry entry that was done without your knowledge.

Then reinstall a clean version of LimeWire from here: http://www.limewire.com/english/content/download.shtml

Good luck