Java 1.4.2 or 1.5 'should' be fine for all versions of LW.

Generally forced restarts are due either directly/indirectly to a hardware issue.

Can you tell us what graphics card brand, model & version drivers you're using?

Re: firewalls; did you configure them to give LW full access?: http://www.limewire.com/english/content/firewalls.shtml
(That's a side issue.)