I got the same problem. It happens when I get a loading screen at a round ruin with a quest-marker "Rhode"
Here is a screenshot of the ruin I mean:
http://i49.tinypic.com/9hlxj8.jpg

My system:
Intel Core Duo E8400 3 GHz
4G RAM
ATI Radeon HD 4870
Running Windows Vista SP1
All drivers updated to latest version

I have already tried re-installing the game completely and starting a new game, and running the game in extremely low quality, but it doesn't help. Is there a way to solve this?

On the page about the error ( http://support.microsoft.com/kb/125749/en-us ) it is written that the error is happening because of a bug in the code.