I am having the same problem. If I try to launch with the FNV4GB or NVSE the game hangs at the Bethesda logo. If I try to launch with falloutnv.exe it crashes. It does not matter whether I have any mods enabled or not. I played earlier in the day with no issues and now I can't play. I tried the blacklist.txt file and no change in behavior. I am running win7 ultimate 64-bit. I can launch the game from steam and I can launch Skyrim and Fallout 3 with no problems from MO, but not New Vegas. P.S. I haven't played Skyrim for a while and the MO version for it is still 1.2.14. Fallout 3 uses 1.2.18, though it is not a steam game on my system. Verified game cache, etc., etc....