Reinstalling LW will normally uninstall any previous version. Else, you can go to the Start menu > Programs > LimeWire > Uninstall.

Yes using the add/remove control panel can cause problems.

BTW did you use CCleaner as recommended? It's a very good utility! Clean up your registry & then try reinstalling LW. CCleaner will give you a list of out of date or unused/obsolete registries. No point having junk sitting around your system. Besides it can potentially cause problems as may have happened to you.