So this has started happening to me more often lately. I have no idea what's happening. At all.
So, I jump quite a bit. I find myself automatically pressing my jump key when I move around, so I end up hopping like a rabbit sometimes... And this is where the problem starts.
Every so often... Something happens. Something strange and magical. I get transported, suddenly, without warning, to the realm of Aetherius, and clearly my computer cannot handle the divine presence of raw magicka because I drop to 10FPS instantly.
I am unable to see my character, my skill bar, my crosshairs - nothing but the blank, grey void and the occasional whispy cloud moving overhead. I cannot even move my camera up or down, only left to right.
Typing /stuck doesn't work, because when I respawn I'm still there. If I type /stuck twice, or three times, the same things. In fact, if I do it too quickly from the previous /stuck my entire PC crashes forcing a manual restart. Relogging doesn't work either, before you ask - the only thing that works is completely quitting the game and then re-entering.
When I re-enter, I see this:
http://oi57.tinypic.com/vdcry1.jpg
At this point /stuck works and I can continue playing as normal, but this is still a very strange and annoying game breaking bug.
I've noticed it happens more often if I jump while standing on top of some objects in the game world, like tables and so on. I once jumped on (and got stuck in mid-air between) three NPCs standing close by and talking to each other, and when I jumped there to try and escape this happened.
Other than that, sorry I can't give any more info.