I had one game breaking bug in NV that made me rage big time. Couldn't level up my character attribute because the button for it was blacked out on the screen where you pick from the list, so I was stuck in that screen after every time I reloaded it and went to that level up screen.
My game save was corrupt so I couldn't fix it. I've heard of it happening to players at lower levels and they had to start over. Of course it happened to me when I hit level 30. I wasn't about to play through it again at that point.