Return of Reckoning

I don't know why but when I press g or try to look up guild it freezes the game.

Check your bindings/hot-keys. Do you have anything else bound to G? Go to your user menu and try removing G as the binding to bring up Guild menu, see if G still locks you up.

If that's the case, what addons do you have running?

I have experienced similar effects on non guilded toons and hitting the guild key out of habit. All players and NPCs disappear and I have to force close the game.