The first thing I would check via the Task manager (crlt&alt + delete one time) is what program is using so much resources. Look at the Process tab (click two times on the CPU bar to bring the most used CPU on the top). Check whether there are two LW exe running at the same time. If so, kill one of them via "end process.
Updating the Java version (to 1.5.0_07) would be the next thing on my list. You can get it here (choose the JRE offline installer):
http://java.sun.com/j2se/1.5.0/download.jsp
Before installing it, make sure all older versiona are uninstalled. Best to reboot after uninstalling the old, as well as after installing the new one.
