If still doesn't work, then check the Java version that's running. If using OSX 10.5, then make sure Java is 'at least' Java 1.5. If it's already set to Java 1.5, then try Java 1.6 as that sorted the issue for at least one user;
Setting up Java 1.5. Good idea to log out & back in after changing Java preference settings.
* If you are using LimeWire version 5 you will require Java 1.6. How to organise your java preferences as shown below may vary per person's set up. LW 5 users may need to move Java 1.6 up higher than shown here, such as 2nd or 1st on list.
Non intel users, OSX 10.4 & earlier OSX users will not be able to use LW 5. Users whose computers are not 64-bit capable intel machines, are limited to LW 4. Such OSX 10.4 & 10.5 users will be limited to LW 4.18 using Java 5 (1.5). Make sure your Java 1.5 is high up on the Java preferences list.
(Oh & the beta fixed it for someone too, however, beta versions may have bugs of their own.)
* Edit: Java preferences for Leopard OSX 10.5
Below are settings I am using for LW 5 beta for Leopard OSX 10.5. Those users who do not see Java 6 (1.6) listed in their Java preferences for Leopard are not running a 64-bit capable intel computer, & thus will not be able to use LW 5. You would be limited to
LW 4 _ (click link to see how to downgrade).
OSX 10.6 Snow Leopard preferences sample image below:
(click to see larger view) .