HP LP2475w acting strange

[palladium]

I have a dual monitor setup, one HP LP2475w and an old Dell 15". The HP is connected to my GTX280 via a DVI cable; the Dell had a VGA-DVI adapter. Now strangely whenever I start the computer the HP does not display anything until I reach Vista's login screen, only the Dell displays the POST screen etc ( the same thing happens when I enter BIOS). I tried disconnecting the Dell from the video card, did not help. There were no display related settings in my BIOS ( GA-EX58-DS4 rev. F3)

Also, in Windows at least, the OSD option for image control ( which I believe houses the scaling options) is greyed out.

Does anyone know of a solution to these 2 problems?

Thanks