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My workstation has two monitors and Windows 7 (64bit). Sometimes when I lock my computer and later return and unlock it, the second monitor won't wake up. I have to turn that monitor off and on to get the picture back. They are identical monitors. The "#2" monitor is set as the main display, if that matters.

I glanced at the power saving settings but didn't see anything noteworthy, and I'm not sure what I would be looking for (or if that is the right place to look) in the first place.

Addendum: it also happens other times. E.g. I want to run a batch file I am working on as administrator. The screen flickers as the Win 7 dialog pops up prompting me for approval. Sometimes when that happens, monitor #2 doesn't reappear (that has happened three times in the last two days, over several dozen such instances).

Other particulars:

  • Monitors are Dell E197FPs
  • When the secondary monitor does not come back on, windows still recognizes it as best I can tell. E.g. if I go to screen resolution it shows both monitors and I can change settings on both.
  • Video Card is an nVidia geforce 7600 GS.
  • "Monitor #2" (again, set as the primary) is plugged into the DVI port via a DIV -> VGA adapter. "Monitor #1" is plugged into the secondary VGA port.
  • Drivers are v197.45

It's not the end of the world but it is annoying. Help?

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1. What is the make/model of the monitor, type of cabling (VGA/DVI/DisplayPort/etc), and the type of video adapter on the PC? 2. When the second monitor is not working, does Windows still think it's there, or does Windows think it has been disconnected? – Miles Erickson Apr 22 '10 at 19:17
Details added (thanks for prompting me to add them). I'm going to check out the drivers as per Sefler's suggestion, though I need to check in with our hardware guy before I do anything of course. – peacedog Apr 23 '10 at 12:50

This may be caused by your Graphic Driver. Try to update it. My laptop has Mobility X1600 and suffers from the same problem. But since AMD doesn't provide drivers for Mobility X1600 any more, I can't solve it.

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My drivers appear to be up to date (197.45; I've been really busy and couldn't get back to this right away). – peacedog May 6 '10 at 13:44

What worked for me when the second display did not wake up:

  1. Update graphic adapter drivers (Device Manager -> Graphic Adapter -> Update drivers)
  2. Send the computer to sleep
  3. Wake up
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