This bug can be reproduced when you do Yes Man's quests, after his version of saving the president. If you then work for the NCR, they will give you the same quest of saving the president. If course, this is a bug and the game stops. It asks you to talk to Ranger Grant, but you cannot initiate ANY dialogue with him, unable to progress.

Some say use the command "setstage 00136166 100" to end the quest manually, but this is a poor workaround, as if one uses this to complete For the Republic Part 2, Legate in the end quest never appears.

Note that this is different from the Ranger Grant bug where the only thing you can say to him is "goodbye". Disabling him and re-enabling him (resetting his character) does not work for the former bug.

Any idea how we can get through this? Is it possible to "uncomplete" a completed quest in the past? I am thinking if we mark the Yes Man's quest version of saving the president to "not complete" we can then talk to Ranger Grant properly.

Obsidian, please fix this. You are highly notorious for releasing buggy games.

I have the same problem, except that I protected the president with Mr. House's quest, I then disabled Mr. House and killed Yes Man to try to align with the NCR. Now my "For the republic, Part 2" quest is stuck at the "Talk to ranger grant..." step. I think this is a scripting bug that requires a patch.