Recently my NVIDIA GeForce8400GS graphics card with dual monitors (ASUS MS227 vga/DVI-D) on a Windows 7 64-bit PC was working great!
Then, I downloaded a Keil C Compiler (MDK420.EXE) and ran the install. At the point when USB drivers were installed, my second screen (DVI-D) went black. I have tried uninstalling the Keil software, uninstalling and reinstalling the NVIDIA driver (270.61), swapping monitors, booting with just a DVI monitor connected, and so on. Still, the DVI monitor is not recognized.
Keil's response is : "We have had thousands of downloads and no problems"
To NVIDIA's credit they are working with me, asking that I try simple experiments. What I was really hoping for is some way to inspect the PlugnPlay registry values, as I assume that if a monitor is not detected, the problem lies there. Windows 7 has a new way of doing dealing with displays (QueryDisplayConfig and SetDisplayConfig), so not too surprising that there could be a new problem.
I advise you to unplug any secondary DVI screen before you install this program!
You are correct, this is an alleged cause and effect. However, it is repeatable. I was able to restore dual monitors and then try a Keil reinstall with the same effect at the same point. What kind of evidence would be more convincing?