Well your specs all seem to be in order. I hope a windows expert will pick up on this as I use a Mac. I'm not really sure where the problem might lie. I just have vague memories of PCs crashing with far greater regularity than Macs
Have a look thrugh this thread.
http://www.gnutellaforums.com/showth...ighlight=crash
I would be inclined to do a complete reinstall of Java after uninstalling Limewire along with it's preference folder
and then reinstall Limewire, both times using the downloaded installers.
This is explained in Fixes for Limewire in the second post.
There are other ideas in the post, and this seems to be fairly similar to your problem, so see if it helps.