Two days ago, I installed Windows7 and it worked perfectly. Then I installed Assassin's Creed Revelations, played for around 20 min and the computer restarted and windows won't start. I installed Windows7 again and now I get a message that says CANNOT DISPLAY THIS VIDEO MODE, CHANGE INPUT TO 1440X900@60HZ. I can't start the windows normaly and not even in safe mode.
More aboutcannot display video mode
if you hit F8 at boot up, there should be an option to boot with VGA
Once you get it to boot via VGA (above), install your video drivers and it should support the correct modes for your display.