First off, I have to say I'm really enjoying this game. This is my 3rd play-through and up until this point have not experienced any bugs.
I recently ran into a problem at The Garage, with Boris. I did some trading with the guy at the garage, went up on the roof, went onto the broken building closer to the exit to loot, then clicked on the exit icon on the map. I automatically jumped down, almost got to the exit, then turned around, climbed up onto the broken building, then climbed AGAIN onto the very top of the structure. From there, I could run back and forth on the very top of the building, but couldn't get back down. The Run to Exit option didn't work, nor would any of the action icons down below. I could click anywhere up in the sky to move myself left or right on the top of the building, but could not click anywhere below.
I waited 4 or so hours for Dawn to come, and eventually Boris returned home (wounded, of course).
Also, I was planning on taking a screenshot in order to show the result of the bug, but I noticed that my print screens were coming up all black. Is that intended?