I am currently running KSP 1.9.0.2781 64bit on Windows 7.
When launching KSP from steam, the game starts up Just fine, and the Main menu opens. The three kerbal float around and the music plays Just as normal. I can click all the buttons and they do react by changig color when hovering by then, but none of then seem to do anything. (None of the buttons lead me to any other menu)
Reinstalling the game does not help and i did not ever encounter this issue before the 1.9 update.
I would strongly appreciate any responses helping me solve this problem.