REALLY weird issue I'm having. Never had anything quite like this before in any game.

So trying to play Skyrim. I get the Skull of Corruption and am about to leave the area where you get it, when suddenly my game goes from 45-60FPS to a consistent and solid 10FPS, with very delayed movements. Reloading my save game takes about 3-5 minutes (from less than 30 seconds) now too.

What is even weirder, is that this suddenly starts happening with all characters, and all my saves. All of them take minutes to load, and run no more than 10FPS. Restarting the game doesn't help.

No mods.

My PC:

2500k i5
560Ti
8GB RAM
Xonar DG sound card
Windows 7 64bit Ultimate