Weird lighting issue?

[Fishsuds]

So, I'm running Skyrim through steam on Windows 7, which I'm running through bootcamp on an iMac. (I know, I know...) It used to run really well until what I assume was a recent update? I assume Steam automatically updates the game for me, and since it has, I've been having a strange lighting issue that's making the game incredibly frustrating to play.

 

My game apparently doesn't feel like saving the screenshots I've taken, but it's almost like the game can't figure out how to transition from, say, a shady area under the trees to a bright and open area. The lighting is on the fritz. One minute it's sunny, and the next it's a very glitchy, line-y/crosshatchy shady with lines of brightness inside.

 

I feel like it has something to do with the shadows, which are on low quality anyway. I tried setting it to ultra which didn't fix the problem, only slowed the game down. Is there a setting I can change, or turn off/on to fix this problem? It's driving me nuts! I'll try to get a screenshot of what's happening as soon as possible.

 

 

Here's some more technical info..

 

Graphics Adapter: ATI Mobility Radeon HD 2600 XT

Aspect Ratio: 16:10 Widescreen

Resolution: 1680 x 1050

Antialiasing: Off

Anisotropic Filtering: Off

Detail: Low

Texture Quality: Medium

Radial Blur Quality: Low

Shadow Detail: Low

Decal Quantity: None

FXAA is not checked off.

Water is set to reflect the sky only.

 

 

Please help! ):