Hello!
What version are you using?
When did you download it?
If you downloaded it Friday or later and are using version 2.9.8 then you have downloaded the corrupt version the so called version 2.9.8.2 for Classical Mac OS. The solution is to use Sherlock 2 and search for LimeWire and delete everything LimeWire on your system except the Shared Folder ofcourse.
Then go and download the healthy version 2.9.8 that was released prior to Friday. Get it here:
http://www3.limewire.com/download/2.9.8/
and install that one instead and it should work.