Windows 7: No video display on laptop until login screen

Recently and all of a sudden (perhaps after using a VGS projector) when i boot my laptop i do not get any video display - not even my TOSHIBA POST or the "starting windows" screen. But when the boot gets to the login screen it dispalys on my laptop and from thereon everything is fine and normal

If i connect an external monitor or projector i can see everything right from the very beginning on the external monitor such as the TOSHIBA POST and the starting wndows etc. When the login screen appears the dispaly from the external monitor dissappears and the dispaly returns to my laptop screen after which everything is normal.

I have installed (and reinstalled) the latest video card drivers for the ATI card
I have reflashed the bios
I have reset the bios setttings to default
Since i image my computer often i restored two previous images of my system drive but to no avail
I have NOT reset my CMOS as i do not know where to find the battery inside the laptop

What can i do/try to get back the display of the boot which was very much there a few days earlier

thanks

When you recently used the projector did you switch the screen output to just the laptop screen instead of leaving it in the "mirror" or "projector only" mode? You probably left it in one of those modes, which is causing this. Hit the Windows + P combination to make sure you're in the default laptop screen only mode.