Have you checked the Limewire folder for any log files? I just recently began having this problem as well. At times, Limewire would shut down and then freeze my computer! I found some intesting stuff in them. They're worth a look (my problem is somewhere in Limewire.jar where a EXCEPTION_FLT_DIVIDE_BY_ZERO error is created. I have half a mind to personally decompile the jar and try to fix the error).
Yeah well, anyways, if Limewire has crashed, you might be able to find some log files.

Good luck...