When I interact with the Arcaneum Vendor, I click "Can we see your wares" dialog option, the screen goes dark for a second, but returns to the party view. The video gets choppy, and I'm unable to move my characters. If I mouse over the screen where things should be, I do see the tooltop for items, but I can not see them. When I hit the ESC key, I briefly see the open wares windows before fading to the normal UI.
EDIT: Upon reloading the game, the vendor is working again.