Windows 7 Start Screen Freeze

Hello,

I've bought a new graphics card today: ATI Radeon HD 5770
Booting the computer on ubuntu works fine, it detects the graphics card flawlessly.

On windows 7, I get to the start screen with the coloured windows icon and the black
background. After that I hear the sound that appears on the login screen. The screen
stays black with the coloured windows icon in the middle though.

I can enter my password and press enter... I'll then hear the startup sound. I can also
hear my anti virus program saying that the anti virus database was updated.

That's why I expect the problem to be at the screen driver, but I can't change or
uninstall it, because it won't let me view the screen...

Does anyone know a solution?
Maybe a combination of keys that resets the current screen settings?

Thanks in advance already,
Thomy

Boot up in safe mode and uninstall your video driver, then reboot.