I've seen same problem with others. Not sure if there was a simple answer. Have you tried deleting your LW preferences whilst LW is closed: Deleting LW Preferences folder in OSX.
Something else to try, might not make any difference is to move the Java 1.6 up or down on the Java preferences before opening LW: Setting up Java for Leopard.

Another alternative is to get LW 4.18 pro instead. It has more tools, less bugs & is more stable than LW 5. Pro download page (click 'Classic' link on left side of page) (click 'this' link to see image). However if you do decide to get LW 4.18 instead, you will need to remove the install limewire.pkg file from the Receipts folder for it to install; Receipts folder sample image