My HUGE glitch is in the "Empires Questline" at the end of the very last quest, "Battle for Windhelm". You are meant to battle your way through Windhelm to get to Ulfric, and when you enter his chamber, you sheath your weapon and just freeze still, and so does he. You can use Unrelenting force as soon as you enter to stop this, but as soon has he goes to his knees you cant kill him as the General is not there!!
This means the quest can not be finished and you cant leave the room untill he is dead!