Windows 7 - Blank screen after logon - need help

I did an upgrade from Vista Buisness 64, to win7 Ultimate 64. Dell Latitude e6400, with Nvidia Quadro NVS 160M. In general, everything went quite well. Except - when I boot up, I get to the logon screen, I hit Ctrl+Alt+Delete, and I log in, then the screen goes blank. If I hit Ctrl+Alt+Delete again, I get the screen where I can switch user, change passwords, log off, etc. If I cancel this, I get blank screen again. If I reboot in Safe Mode, all is fine. If I uninstall the NVidia driver, then reboot normal, I can log in, but the system is using Standard VGA driver. I have tried various drivers from NVidia, LaptopVideo2Go, Dell (win7 - 181.71, 181.72, 185.81, 185.85, and Latest Vista driver from Dell site). I've tried installing from normal mode, safe mode, I've tried DriverSweeper, I searched the registry deleting all references to the drivers I can find...). One time I did somehow get 185.81 working - I don't know how. It was running fine 5 five days (I did not reboot during that time, just sleep mode), then I got a blue screen, and back to the blank screen after logon on the 1st boot. I screwed with the system for another day, and finally got the Dell Vista driver to run once. Once again all was well, until I put the laptop to sleep in the docking stn, then woke it up - blank screen again.

I'm typing this msg now with the standard VGA driver. The 2 things that bother me about this driver, are only single monitor support, and the machine will not go into Hibernate or Sleep mode with this driver (not to mention the speed of the driver).

I've already spent far too much time trying to solve this problem - any help would be *greatly* appreciated.

Thanks...

 

simple answer to your problem really,
never ever ever ever ever upgrade an OS, weather it's windows - mac os or linux

always clean install