I can still see my UI such as my sneak icon but my surroundings go black and if I turn left or right they will sometimes reappear, if I stand up (going out of sneak) then the screen will no longer be black.

I am a nightblade female dark elf


edit: this only happens on my nightblade and only in peoples homes, not outdoor

It's the nVidia fog bug, it happens on nVidia cards when cells have certain fog distance values. There are fixes avilable, such as this one: http://www.tesnexus.com/downloads/file.php?id=11167. Personally i use the the fix included in http://www.tesnexus.com/downloads/file.php?id=22368 bashed patch, as that fixes mods cells too.

In addition to the fog bug mentioned above, it is also related to the interior shadows graphic setting for some of us. This is the case with me. The "Nvidia fog fix" mods do not work for me, the problem only goes away when I completely disable interior shadows. There doesn't seem to be any true fix for this, as the mod that fixes it basically allows you to set a hotkey to toggle it off when the problem occurs (quicker than going in the graphics menu) or does it automatically. Link: http://tesnexus.com/downloads/file.php?id=13632

Your character closes his/her eyes. Happens all the time. Makes the game more realistic.