Steam Install won't work on Windows 7 (KSP 1.9)

[The Dressian Exploder]

So, basically what it says on the tin.  Freshly installed KSP 1.9 with both expansions. Clicked play and I get a window called "Kerbal Space Program -Unity {NUMBERS}" with the KSP icon and a progressbar, but the window closes before the progressbar fills. Using Windows 7 Home pro. Anything else I need to specify?

[Harry Rhodan]

It's either a driver issue or you need to force the game to run in DX 9: