Sounds like you have a worm, use this method to get rid of it....
http://www.gnutellaforums.com/231269-post141.html
Once you have done that, could you try entering limewires Tools > Options...Can you open it, or does it close immediatley ??
If you cannot open it, you have another trojan...
To fix this you need to install AVG antivirus....
So disable the current AV you are using - install AVG and make sure you UPDATE it and run a full system scan....
Follow the prompts on what it catches....
Then you can uninstall it and go back to your normal AV...
AVG free (click on link)