Cannot launch Java application

I'm probably posting this is in the wrong section, (i don't exactly understand java) but anyway!! (PLEASE READ)

I'm trying to play this game (RuneScape) that requires Java, and they have a client for Mac OSX (which is what I have) but when it loads the application this
message comes up:

Cannot launch Java application
Uncaught exception in main method: c


So I updated to the latest Java, and the letter "c" changed to "b". And now it's back on "c" after a week or so. When I try to play it in a browser the screen says black after the RuneScape title thingy with a spinning light wheel thing, comes up as it if it's loading. but then it goes and the screen goes black.

So can anyone tell me what this message means and if I can fix it somehow?


Thankyou,

P.S
I posted this on RuneScape forums, but I didn't get much - just people with a similar issue...

You need to ask the author of the program about his code and why it does not catch the exception where it should.