I still can't find it! I've spent… I don't even know how many hours now running around

The only "big" temple I can find, which is east of the bandit camp, is the one northeast leading into the volcanic depths. And I've still not found any disc in there, only the two blue barriers I can't get past.
I've taken a picture of the entrance I am talking about here http://img39.imageshack.us/img39/4932/mapwc.jpg

I have talked to Fincher, and he just says "The big temple to the east, you should know where it is" or some such. But I have no idea what he is talking about, argh!

It is so frustrating, because I have no other quests I can do at this point, and running around in circles is becoming very tiring.