Do you have a PHP error log? Have you tried installing a clean copy of GS in a subfolder to see if it even works? If it does work, then we know it's with your site. If it doesn't work either you should contact your host; possibly something is wrong on their end.
Edit: probably not something on your host's end; you host with HostGator and they wouldn't just screw something up.
Edit: probably not something on your host's end; you host with HostGator and they wouldn't just screw something up.