Obsidian developers have asked that MotB issues be reported on the forums:

Everytime I try to enter the gate to the City of Judgement nothing happens. After I click "Enter the Gate bla bla", I can run around but can't use the left mousebutton (I can't even load a game) and the spirit meter stays grey.

I tried it with 3 Savegames. One of them was 1hour before the gate.

So.. Do I have to play through the whole game again?

Is it because Safiya is missing? I killed her, the Founder and Araman.

There is also an exploit in the Icetroll Lodge while playing multiplayer.
You can't lose any of the trials if you are not alone. I died several times in the pool and didn't die because of the other guy in my party.
Same goes for the fighting trial.

After that we stopped playing coop. There was another bug which only appears in multiplayer. Many NPCs had duplicates of themselves, like the shaman and his tigers in the lodge or the thief guild trader and his bullys in the tavern (there were 4 of everyone of them)