Why does my Windows 7 boot up to a black screen after login?

I had a similar situation on my laptop, except it just stayed at the black screen. I could still boot fine in safe mode, but normal mode would just go black. Eventually I figured out that while win7 had identified the correct video card, it installed the wrong driver. After manually updating the video card driver, my non-boot black screen never happened again. (Though it's not perfect as sometimes when it has gone to powersaving mode and shut the screen off it won't come back up, but this is rare)