That's caused by a virus. Try the fix in this thread(Try it first):
To fix the limewire keeps popping up / no taskmanager bug do the following
More virus info in this thread:
WARNING: Viruses on network you should be aware of!
You can also try downloading AVG(free), update it, and scan your computer:
AVG Free Advisor: AVG Anti-Virus Free. We've had luck with it cleaning some other viruses.