This is an odd post in the hopes it might help someone.
I have spent the last year or so trying to get some of my games to work on my new Windows 8 gaming rig and I recently managed to get Skyrim going again.
The issue was that in the Skyrim installation folder (under Steam that is C:\Program Files (x86)\Steam\steamapps\common\skyrim) there was 2 DLLs: atimgpud.dll and atiumdag.dll.
I'm not sure how that got here, I usually don't mess with my installation folders but I've had this game for a long time and whenever I get a new system I just copy the whole steamapps folder.
So I just erased the two files and that fixed the "Failed to initialize renderer: Unknown error" that I was having.
Now on to slaying some dragons.
