Are you downloading files when LW shuts down? Try reducing the number of simultaneous downloads to 1 or 2. Does it shut down when no downloads are in progress?

Which version of Java are you using? People have had problems with the most recent Java updates (even when other things are fine, LW acts up). So, if you have Java 1.6.0_01 or 1.6.0_02, try this version instead. Download the JRE offline installer & remove any other Java versions before you install this one.
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11
If it turns out that Java's not the problem, it's easy enough to reinstall a later update

Also try the tips here: Reduce the drag caused by LW

Is LW shutting down at regular intervals (eg every 2 hours)? Not trying to alarm you or anything, but somebody recently had this happen & it turned out to be a virus.
http://www.gnutellaforums.com/connec...premature.html