Some users especially Asus have had troubles installing Windows 7,as there seems to be a bug when using 2 monitors.So if you experience this unplug one of them,and then install Windows 7 again..
If you already have the bug try pushing Ctrl+Alt+Delete and see if it removes the black screen.If not you can try starting in safe mode by hitting F8 just before Windows 7 loads..
Once you get to the desktop open notepad and copy the following in.
displayswitch /extend
displayswitch /internal
Now save the file as a .bat file..You could call is display.bat
Put the file in the windows startup folder..
C:/ProgramData/Microsoft/Windows/Start Menu/Programs/Startup, where C is the letter of the drive Windows 7 is installed on..
Reboot and Windows 7 should load correctly now
Another tip is to remove all USB units except Mouse/keyboard and reboot.