I must assume that to play a gargoye you must have the Stygian expansion?
My ML software did not give me a choice when I first logged in. The client is fully patched.
If you download the client linked on the play free Pandora page and fully patch it, you'll be good to go.
http://www.pandorauo.com/playfree.html (http://www.pandorauo.com/playfree.html)