I'm midway thru the NCR quest where the Legion is attacking Hoover Dam, and I need to make my way thru the generator rooms to get to their camp. My issue being that about after 1 minute of fighting these guys, my game freezes up and crashes. Also, it should be mentioned that during the quest where I was sent to guard the president, the Vertibird landed, stopped for a second, then took off, not having dropped off the president and giving me a "Quest Complete!". Is this common? Is there anything I can do? I'm roughly 12 hours in, so I really don't want to start over.