I have ATI Radeon HD7970, Dell monitor with max resolution: 1920x1200 and windows 7 64bit.
On starting computer: 1) BIOS - all displayed OK 2) Windows loading - all displayed OK 3) Logging in screen - not displayed - monitor is telling me, that best resoultion is 1920x1200. It looks like graphics card is using too high resoultion.
All I can do is putting computer to sleep, waking. Then all works perfectly.