Do you have administrative privilges for the account you are doing this from?

What version of windows are you using?

If XP shutdown the comp and start in safe mode pressing the F8 key

It should give you several options select safe mode.

In start>all programs>LimeWire --- uninstall

Then open windows explorer and go to
C:\Documents And Settings\Your sign on name
then delete the directory .Limewire

let us now how it went.