I don't know if this will help you. I was setting up a Windows 7 system (Packard Bell), for a family relative & have experienced a similar problem.
We installed all the software, and I did a reboot to test it started before I left and it said starting Windows and then I got a blank screen where I could move the cursor about....
I thought for a while the system wasn't booting up properly, but could here the windows start up sound but nothing else.
Almost giving up - I tried a few keyboard combiniations, Firstly the keyboard had a sleep key which I accidently pressed and then moved the mouse and the login screen appeared.
So I tried then rebooting the machine with the monitor off and switch the monitor on after the startup sound - and this seems to work, which would indicate either some driver
issue for me, or also I originally connected the PC with DVI cable only and it required VGA also (which surprised me) - I would have thought 1 cable would have been enough...
Anyway... this information might help you - hope so or it might give someone else some ideas why this might be happening.