Open task manager (ctrl-alt-del) & see if there's any LW process running. If there is, end the process.
When you uninstalled LW before, did you do it thru add/remove programs? That can cause problems. The correct way to uninstall is via start > all programs > LimeWire & use the uninstall option there. Usually, installing a new version will automatically remove the old version.

If you can't install a new version, you might have to use your computer's search to look for LW files & folders & delete that way.