First of all, you should make sure that the Limewire player is not your default player. Tools...options...player...untick 'use LW player'. After you do that, files should open in your default program for each file type.

You say you have the most recent version of Java. Does that mean you have version 1.6.1? Some people are having trouble with that version. You could uninstall that via add/remove programs and reinstall this version:

Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11

Good Luck

Dan