When LW 4.12.4 is released which should be within the next 24 hours with luck, then get it http://www.limewire.com/english/content/download.shtml
It apparently addresses issues "some" people have been having with LW crashing. This might not fix your problem but it's a good place to start. If it doesn't fix it, post back & let us know. In that case might ask you to run a console report which may show where the problem is.