Graphics Card works great, but not during POST!

[sdog]

I'm not sure if this belongs in the MOBO forum or the Graphics card forum, but I'm inclined to think it's MOBO so here goes:

Once my machine boots up into Windows, the graphics card works beautifully, no problems, no conflicts, beautiful display.

However, until it gets there (i.e. during POST),  the display is extremely dark and semi-unreadable. I can see the little "energy star" logo in the top right corner and the row of very dimly displayed  action key indicators ("DEL" etc.) along the bottom. All of the scrolling POST text is non-existent (I presume it's really black-on-black, not non-existent, but I can't see it any more, so hey, how would I know?...). If I press DEL to go into the BIOS, I can see some of the BIOS text (very dark/dim), but not all. Some (like the help text) is black-on-black or non-existent. Makes it a pain to change any BIOS settings.   

It all worked fine for a while when I first assembled the machine, but at some point it started doing this and has been for a very long time. I just haven't had time or inclination until now to try to research the answer, since I don't often dink around in the BIOS. Has anyone seen this before or have any ideas about where I might start looking to find the cause?

MOBO=Gigabyte GA-EP35C-DS3R - BIOS=F4 - Drivers=latest as of 2010-04-12

Graphics=Gigabyte GV-NX86T256H - BIOS - not completely sure - for some reason F21 is sticking in my head, but I can't recall where the display BIOS is reported in order to confirm. - Drivers=NVidia 197.45

Monitor = Micron 900LX SVGA CRT (think this is actually made by Panasonic ) connected to GV-NX86T256H through DVI-VGA adapter.

OS=WinXP SP3

Thanks in advance for any ideas you might have.

 

[Fatman]

Can you try hooking up to another display to rule out the  monitor? Checked the contrast/brightness settings on your display panel??

[sdog]

Thanks Fatman, but I don't have another monitor around. Contrast and brightness settings are fine. 

Anyway, I'm finding it hard to understand how it can be a monitor problem since monitor, MOBO, and graphics card all perform perfectly... once Windows loads. But I truly don't understand exactly how these three pieces communicate with each other during the POST process, so maybe different parts of the hardware (on the MOBO? on the graphics card? in the monitor?) are being used during POST than when up and running? I was hoping  someone might understand well enough how this interaction takes place to shed some light.