This is most noticeable in very snowy regions. The grass, flowers, leafs and similar will have something like an aura of shadow.
The thing is, each time you move, or your third person camera moves, the shadows will flicker in an extremely noticeable and annoying way.
Even in 1st person, if you approach and look, a smaller flicker is still there.

I've put several .ini tweaks and graphics mods, so I wanna know if this is an issue of mine or several of you are experiencing it.

Thanks!!

I have been having the same issues, and they have been driving me nuts as well. I have no idea how to fix it, sadly.

I have also noticed that when this occurs, if you go to the "Wait" menu, your character is surrounded by blackness.

For mid-high end PCs:
iShadowMapResolution=4096
iShadowMaskQuarter=5
iBlurDeferredShadowMask=4
fShadowDistance=2500

For low-mid end PCs:
iShadowMapResolution=2048
iShadowMaskQuarter=5
iBlurDeferredShadowMask=6
fShadowDistance=2500

The real issue cannot be solved by .ini tweaks and others. Only a serious patch..with nothing seriously hard to change really if Beth would finally would start really patching the game.

Check this article out, refer to the first set pictures to the problem.

Common Techniques to Improve Shadow Depth Maps
http://msdn.microsoft.com/en-us/library/windows/desktop/ee416324%28v=VS.85%29.aspx

not even close to the real issue i'm affraid.

You wouldn't happen to have Hardware Forced Ambient Occlusion on, would you? As in, you have enabled it through the CCC or nVidia control panel?

I know that this was a problem when i was using SSAO forced through nvidia. Unfortunately, as pretty as the game looks with it, there are problems like this, or occlusion shadows that show through fog and water.

I disabled it, as the shadow shimmer is way too distracting.

Hope this helps!