Update your Java. Use the JRE offline installer & remove your current Java version before you install the new one.
http://java.sun.com/javase/downloads/index_jdk5.jsp

If things are freezing only when you're using (I guess you mean downloading) LW try these:
In LW tools > options > speed. Disable ultrapeer capabilities.
Reduce your upload & download bandwidth a bit.
Don't download too many files at once, just 1 or 2...same for resuming incomplete files.
Disable iTunes sharing.