This happened to me once before when doing the sidequest mission to save Matt where the game would hang on the loading screen forvever. I was able to solve it by doing some of the side quests first then trying his mission again. However, I just encountered this again on the "Girl who hates the 50's" quest. After the Rally with Keith when you kill all the enemies inside it tells you to enter the office upstairs, when I do this it just gets stuck in an infinite loading loop. I minimized and checked the task manager and the game was not frozen, just loading indefinitely. From what I've read around the internet this is not an isolated problem as others have been encountering it both on the pc, xbox and ps3. The only fix I've seen recommended is to restart the game. I DO NOT WANT to restart the game this close to the end. I tried older saves as well as reinstalling, removing all mods and upgrading graphics drivers and nothing solves the problem. I would be eternally grateful for either a fix to this or for someone to provide a save close to or after this point. I can't progress until then as this is a gamebreaking bug.