Someone had the same problem a while back - after a Windows update and a reboot, I only see a black screen with my cursor after I login. The previous post mentions removing AlienRespawn because it created a conflict with Windows, but I don't even see AlienRespawn installed on my PC. So that can't be it.
A system restore usually gets me back running but that means that I can't install any of the Windows update.
I have an AlienWare Aurora ALX, 12 GB running Windows 7 Ultimate with a GeForce GTX 480 and i7 x980.