Unity starts but shows me nothing

Are you using the free version or the... you know... the "free-pro" version?

I get similar errors when I come back to my computer after it has been locked (I have to hit Windows+L when I leave my desk at work). When I return, all areas and windows in Unity are pitch black, but the program is still running fine. That is, I can click File, Edit, View... etc, and save the scene just fine, and restart the editor. It's still working behind the curtain, it just stops rendering its own windows. If I close and restart the editor, it's fine again.

I suspect this is the same, except more severe, since you get it right from the start. I told Unity about it, and they said it was related to the graphics drivers. Indeed, I don't get this error with the same version of Unity (and the same project) on my laptop, which has a different graphics card. Try updating (or downgrading) your card's drivers.