today I got Dawnguard, I installed and activated it, the I started the Game. In the main menu screen the "Skyrim logo" appears and on the right side the menu would normally appear. But in my case the menu doesn't appear, instead I get an error message telling me that Skyrim doesn't work perfectly and the game has to be shut down. The problem doesn't appear if i don't activate Dawnguard. Hopefully somebody knowns a solution. I HOPE you can help, thanks in advance.
PS: I use Windows 7 ...maybe this means something.