Windows 7: After update, primary display cuts off after KVM return

This problem seems to be a stumper - 4 days and no replies. Does anyone know if this is more likely an Nvidia issue?
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Since the 10/13 Windows 7 patch, my primary display (left-side, on DVI, not connected to my single-VGA-monitor type KVM) loses signal from my Nvidia GT 240 when I switch my KVM's focus back to my Windows 7 system, and my second display (right-side, on VGA, connected to my KVM) becomes the only display (with Start button and all) as if I had disabled my left-side display. When the KVM is switched to another sytem, my left monitor gives me access to the primary Windows 7 display via a second mouse and keyboard and this still works fine - until I switch back to Windows 7. When I open the Screen Resolution tool and click the Detect button, my dual-view configuration is instantly restored with all desktop icons back in their proper places.

This problem did not occur before the latest patch install, which required a shutdown. Is this a known problem? Is there any way to prevent my primary monitor from being cut off when returning the KVM focus to my Windows 7 system?

It's a typical EDID feeding issue with your KVM switch.
Windows 7 system requires checking the status of connected display all the time via the DDC-EDD channel from your connected display (no matter you connected it directly or via KVM switch). If your KVM switch did not support "full-time active EDID " feedback, the Windows 7 will "think" the display had been disconnected while you switched away/changed your target systems via KVM switch.

Solutions:
1) add "EDID emulator" put between the connected Win 7 system video output and the existing KVM switch.
2) Simply change the KVM switch which support "full-time active DDC EDID".

Thanks, Rex. Interesting solution, and it certainly appears valid after looking into it (now that I know what to look for, that is).

I still have to gripe (not at you, of course!) because this was not a problem until either Nvidia or Microsoft "patched" the code. I wish they would stop "fixing" what is not broken. Now, I need a $70-$100 piece of hardware to trick their patch and get my system/KVM/monitors working like they used to.

Does anyone know the last Nvidia driver version that did not have this fix (sic)?

-James

James,

I too am going through the same thing that you went through with my IOGEAR KVM Switch. It was working fine and now it does the same thing you stated. Monitor on left is Primary and Monitor on Right is Secendary. Everything works fine then when you switch it back over the Primary on the Left is not detected and I have to go into the resolution and do a detect and then it works fine. What a pain everytime. So have you been able to get a permanent solution?
How do you do this? Not exactly sure what that is. Is that a different video card?
add "EDID emulator" put between the connected Win 7 system video output and the existing KVM switch.

Rex,
I too am going through the same thing that James went through with my IOGEAR KVM Switch. It was working fine and now it does the same thing you stated. Monitor on left is Primary and Monitor on Right is Secendary. Everything works fine then when you switch it back over the Primary on the Left is not detected and I have to go into the resolution and do a detect and then it works fine. What a pain everytime. So have you been able to get a permanent solution?
How do you do this? Not exactly sure what that is. Is that a different video card?
add "EDID emulator" put between the connected Win 7 system video output and the existing KVM switch.