Mega 180 - Install Video Card or Install Video Driver

Question

I just spent 6 hours at a customer's house trying to fix the Mega 180 I built for her.  
As I stated in a previous thread, the machine was working fine and then she experienced the BLACK SCREEN OF DEATH.  This is when your machine POSTS, loads Windows and just before Windows starts, the monitor goes dead.  Windows still loads and if you remember where icons are on the desktop, you can click them and stuff happens.  The monitor just stops getting a signal.  However, if you hold down F8 during boot and chose VGA mode, you can use Windows in VGA mode.  The monitor being used is a Sony Multiscan200ES.
Once in Windows, if you look under device manager, you'll see a listing of Unknown and under that it lists nVidia GeForce4 MX Integrated CPU.  
So, I've tried the following fixes:
1) Uninstalled all chipset & viideo drivers, reboot, reinstall chipset drivers, reboot, reinstall video driver, reboot.  BLACK SCREEN OF DEATH.
2) Uninstall video driver, reboot.  Windows starts under the generic driver.  I install the video driver, reboot, BLACK SCREEN OF DEATH.  
3)  Figuring there had to be an easier solution to this problem, I installed an ATI Radeon 8500 card that I had laying around (I know this card works) figuring that I'll just sidestep the whole video driver issue by not using the onboard video.  Things just aren't that easy because after I installed the card the machine won't even POST.  It turns on but nothing happens.  ARRRR!!!  I try reseating the card, nope - nothing.  I take the card out and use the onboard graphics to make sure everything is ok in BIOS.  I read that if the BIOS detects an AGP card it will automatically disable the onboard graphics but it doesn't seem like that's happening.  So I look around BIOS and there is no way to disable the onboard graphics.  I have it set to boot AGP first, etc. and nothing works.
I guess the last thing I can do is reformat the drive, reinstall windows, and reinstall everything else.  But I don't want to do this because the machine is all set up, been used for a while, and it takes so long to reinstall everything.  
My question is this.  How can I either reinstall the video driver so it works or how can I install a video card so it works?  Ideas???

Answer 1

Quote
I'm going to hunt over at nVidia's website to see if they have a cleaner utility (ATI does for its Radeon drivers - rids the system of every last trace).
nVidia don't need a cleaner utility cos their software is better written!  
stab in the dark - the vga lead is connected to PRIMARY vga port?
go to add/remove programs and Remove "Nvidia Display Driver" in Safe mode
restart your computer and it should boot into VGA mode, and prompt with Found New Hardware. cancel this.
the nvidia software will leave the install stuff on your computer, usually in C:\NVIDIA. browse to here and find and run the setup.exe to reinstall the software.
if its been working before, then its probably not a memory issue - it might also be worth making sure the latest nforce drivers (3.13) are installed too.
oh and customers usually WON'T admit to messing around to stuff they shouldn't - in my experience anyway!!