Well the 403 error means it's forbidden. I can only guess that the program is not connecting like a browser would, like having Mozilla whatever whatever in the header (I don't know too much about http, but I think that's right). Also, the website has probably changed the way input works on that page, or doesn't support connections to that page. When I try connecting to
http://grooveshark.com/more.php, I get an error message about no method supplied. Since the program is getting a 403, but a browser isn't, it's almost definitely because of what I explained above.
You can't really do much about it, other than deobfuscating it and reworking some of the code. If you really want to get this thing working, I'm up for working on it with you.