While playing fallout new vegas I was originaly working for Mr. House but at the point when I had the option to join him for hoover damn i decided not to and work for the NCR (after having completed You'll know when it happens) however once completing the questing leading up until You'll know when it happens, I could not talk to Grant anymore and therefore I cannot complete the quest. If there is a way around this please let me know and if Bethesda would please patch it that would be great.