Serious error!

I've had LimeWire installed properly on my system several times. But since yesterday when trying to install it I always get these two error messages:

"Unable to launch Java Application

The property files is missing an essential property: lax.main.class. Please make sure it exists in the properties file: /"

After I okayed this message, another one would come up:

"Unable to launch Java Application

Unable to locate the application's 'main' class. The class 'null' must be public and have a 'public state void null (String[])' method. (LAX)"

After I okay this message, the installer quits. I can't make ANY sense of what the messages say, but maybe someone of you can help me. I've already tried downloading a fresh installer and also reinstalling MRJ, but none of it helps.