OK I started a new playthrough on a new Xbox (last one RRoD'd) and I'm about 25 hours in. For the last 5 hours I've started seeing NPC's animations freezing up - they either stand there in suspended animation with their heads following you around, or they spin round slowly in circles with only their heads moving. Sometimes they slide across the ground as well. It's really creepy.

This is the first time I've played the game with any patches installed. The problem is getting worse the more I play. If I go into an area with 5 people, chances are that two of them will have bugged like this. Even worse, it happens to NPCs during critical moments in quests - eg, when they are supposed to go and unlock an otherwise unopenable door, or when you have to follow them somewhere (an example would be Delvin and Brynjolf opening the vault door in the thieves' guild quest - both of them got stuck instead of opening the door, while Vex was just standing in the background spinning around slowly.) Saving and reloading doesn't fix it, the only thing that works (sometimes) is exiting and re-entering an area.

I'm kind of worried that this is just going to keep getting worse and that it'll make the game unplayable. Does anyone have any ideas how to fix it?