After opening LW, let it settle for 10-20 mins before using. Don't rush it. Also, don't use the Resume/Find Resources button on all your files. If you use it then use it on just one to three at a time. Otherwise it will use up all your computer's resources. Perhaps not downlding too many files simultaneously will also help. Make sure you have up to date Java.

Other tips: Tip: Purge the Downloads Queue!