Unable to enter underground.

Hello the Arcanum and its simply an amazing game however I have encountered serious issues that I cant seem to get rid off.
Number one among them is inability to enter certain areas such as tarant sewers and more importantly Black mountain mines. Let me tell you what happens.
Problem starts when I click on entrance to the area at that point game lags, almost freezes in fact cursor hardly moves and I can enter main menu only with great difficulty.
Map button turns blue as if I was about to enter world map and music appropriate for the area starts to play but thats it.
So far I have tried following: clean install with only UAP applied, previous with -doublebuffer and -no3D, UAP with hires patch and map fixes, all of this while running the exes as administrator and nothing.
Does anyone know what to do?

 

Did you install the UAP mid-game? That causes bugs like this.

For the UAP to work correctly, it has to be installed after the official 1.0.7.4 patch. Also, saves from the vanilla game (or a older version of the UAP) aren't compatible with a later version of the UAP, meaning your playthrough has to be a new game started after all the installations for everything to work correctly.