This is a cause of great frustration for me too,
At first the game would crash 2/3 times a night with either "dirrectX not found" or "Windows has stopped working" error,
I was advised to role back the graphic card software GTS 250, i did that and the "windows has stopped working" error hasnt come back, however I still get the dirrectX not found error, all graphic setting are at standard and i have no fancy settings on the graphics card, we got this graphic's card because it meet the criteria set by SE for this game!
it's not an issue SE have ever mentioned and i'm not sure they even aware its such a problem!!