right click desktop - select properties. Select the settings tab and check the screen res. I had a problem with a system that would load everything ok untill it got to the windows login screen, it would either turn off or just look all funny. I changed the screen res and it worked fine.
Pentium Core 2 Quad Q6600 2.4Ghz
4Ghz 1066 RAM
2x 500G SATA II HDD
GeForce 8800GTS 320MG
Diploma in IT Computer Networking
Bachelor of Computer Science