Was trying to complete the tunnel mission, the crashing is now happening much more frequently! Here is the issue:
While in the "steam room" after Kajika starts up the steam, the agent is supposed to move a lever that lowers the water to cross to the next area. After accomplishing that, game hangs. Restart game, go back to the beginning of that sequence -- thus in the room just before the steam room. Enter the steam room - get to the lever to pull, already pulled. Agent CAN NOT cross over to the new area and cannot escape the steam - anywhere. I would have died had I not had the reviver on. I was able to kill D2 via task manager and my character is still alive.