What version of Java are you using? Try updating. Download the JRE offline installer from here, remove any other Java versions installed (via add/remove programs or Vista's equivalent) before you install the new update: Java SE Downloads

If that doesn't help things...

1. Tip: Purge the Downloads Queue!
2. Within LW's tools > options > advanced > performance, disable ultrapeer capabilities, DHT & TLS > apply > ok.
3. Reduce both your upload & download bandwidth a bit.
4. Within LW's tools > options > iTunes > sharing > untick ' share my music' > apply > ok.

If you're sharing a huge number of files, reduce your amount shared (within LW's library, right click on a file > stop sharing file) & see if that helps.