The following might help people avoid a crash related to entering Drangonsreach. It might have been my particular circumstances exactly that lead to the crashes or it might have been that I had two quests not fully completed at the same time. I dunno, but I post this in case it might be of help to somebody. Playing Skyrim last night and I had a quest to burgle a premise in Markarth. I did the job, but didn't immediately return to Vex who gave the quest. I then went to the Bannered Mare to see if the landlady had any jobs. She told me a giant needed sorting near Whiterun. I killed the giant and then went to Dragonsreach to collect the money from Brill. I tried to enter Dragonsreach, but the during the loading screen my game crashed. I thought this was a one off until I loaded the game again and the exact same thing happened. I was getting a bit concerned now. I reloaded the game yet again and went to a previous save (before either of the quests had been undertaken). This started me in the room of somebody's house. I tried to leave their house and the game crashed again. I can't remember if the quests had been given during that load though. I reloaded the game again from the point where both quests had been done, but I''d not returned to the quest givers. I then just went to Vex, got my money and headed off to Dragonsreach. I was apprehensive as I opened the door, but so relieved to see it load without crashing. I had no more problems then. It's strange how a sequence of certain events can cause a crash.