Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

When unlocking a Windows 7 computer the screen briefly (less than a second) goes blank before showing the screen (this is normal). Abound once a month (but sometimes within 24 hours) when I unlock my computer the screen doesn't come back from this brief blackout and stays black. Sometimes after five minutes or so the display will come back. Other times it has been blank for over 20 minutes, so I give up and restart the computer.

  • It seems to happen more often when the computer has been locked for a longer period of time - I lock my computer several times a day, but the problem most happens when I come in at the start of the day.
  • I have updated my video card and monitor drivers.
  • I have two NEC AccuSync 75F monitors both driven by an ATI Radeon HD 2400 Pro.
  • The computer is a Dell Optiplex 740.
  • When the problem occurs both monitors have a green light on to indicate that they are receiving signal.
  • I've tried unplugging the monitors from the video card and turning the monitors on and off.
  • The screen saver is set to one that is not blank screen.
  • The Windows power settings are set to never turn off the display.
  • When the problem occurs there is no significant disk activity occurring.
  • When the problem occurs I can connect over the network to the hard drive on my computer.
  • When the problem occurs I can't connect over the network with a VNC connection. The VNC client doesn't give an error, but also won't show the screen. The task actually seems to hang as I can see the task, but there is no window for it.
  • This problem occurred when I was running a pre-release version of Windows 7. The hard drive was formatted for release version and the problem still occurs.
  • I've been stopping some of my always running programs to see if one of them may be the culprit, but given the span between failures that will take some time to find the problem if it will even help at all.
  • Some programs I have always running include IE, Firefox, Outlook, Evernote, Kana Reminder, Ditto, Macro Express, Timesnapper, and DisplayFusion.

Any ideas appreciated.

share|improve this question
    
It happened again today. Much sooner than I expected. It came back after 15 minutes. –  Leigh Riffel Mar 15 '10 at 17:17
    
It happened again today. –  Leigh Riffel Mar 29 '10 at 17:12
    
It happened again yesterday and again today. –  Leigh Riffel May 17 '10 at 12:54
    
On 4/28/2010 ATI released a new display driver for my video card for Windows 7 64 Bit. I am installing that now. –  Leigh Riffel May 17 '10 at 13:02
    
It happened again today, so the video driver did not fix the problem. –  Leigh Riffel May 18 '10 at 16:13

5 Answers 5

up vote 3 down vote accepted

I've encountered the same issue. For me, TimeSnapper turned out to be the culprit: if I remember to disable TimeSnapper before locking the desktop I never have a problem.

share|improve this answer
    
Hmmm, I haven't tried disabling that before I lock the computer. Since I lock my computer dozens of times every day that really won't be convenient. On the other hand, I have become dependent on the tool, so I might just have to. –  Leigh Riffel Aug 19 '10 at 12:51
1  
I reported the problem to TimeSnapper yesterday, and I'll report back if they find a fix. –  poco_forte Aug 19 '10 at 22:49
1  
Leigh, can you confirm that disabling TimeSnapper fixes the problem also for you? –  AtliB Aug 20 '10 at 8:03
1  
@atlioddson I rely on TimeSnapper too much to disable it, I'd rather live with the problem as bad as it is. If I knew I could verify it as the cause quickly I would, but since the problem repeats itself anywhere from five minutes later to a month later I don't want to turn it off for a month just to verify that it is what is causing the problem. That cure would be worse than the disease. –  Leigh Riffel Aug 20 '10 at 15:18
1  
@Leigh, can you try running with the pro version (30 days trial) and see if that fixes the problem? (BTW, I'm one of the developers). Although built with the same code-base originally, the pro and classic have diverged considerably. –  AtliB Aug 21 '10 at 11:41

Just wanted to add that I have the exact same symptoms, with no known resolution. I've had a terrible time finding web pages about this particular symptom set, because usually they're about the "black screen of death" where the mouse is moveable and/or the task manager is running. It's good to know I'm not the only one.

A few details:

  • It only seems to happen with my wife's user account, not with mine. I did all the original installation under my account, but she is configured as an administrator, so that shouldn't matter.
  • This started happening sometime a year or more ago. I just last week did a clean reinstall of the OS (Windows 7 Home Premium 64-bit) and it is happening to her again. I copied a bunch of her user data (manually, folder-by-folder) over from the old installation, but nothing that should be involved in the login process (as far as I can tell).
  • Our computer is a custom-built machine, unbranded. The one common component with your setup is we have two ATI Radeon 4850 Pro video cards (in Crossfire) installed. We also have an SSD, but the one in now (an Intel) is actually a replacement for the original one (a $%^& G.Skill), and the problem happened with both. I have upgraded all drivers for all the hardware.
  • The problem doesn't seem to happen if I just create a clean user account, but it's hard to be sure because the problem is so intermittent that it might just be that we don't see it on the few times we try logging in to the clean account.
share|improve this answer

Thanks for such a comprehensive report of the problem! I was seeing a similar problem on my Dell Optiplex 755 computer with a Dell LCD display and NVIDIA Geforce 9800 GT graphics card. It used to happen when I came back and unlocked the computer. After typing the password to unlock, it would lead to blank screen about 1 out of every 3 times!

I suspected that it might have something to do with the display utilities. I was using Dexpot as my virtual desktop manager. I uninstalled it a week ago and have not seen this blank screen problem after that. Maybe you want to uninstall any display utilities you are using for virtual desktops or for dual displays.

share|improve this answer
    
Glad to be of help. –  Leigh Riffel Nov 28 '10 at 3:53

There are numerous other questions with similar issues: http://superuser.com/questions/79421/windows-7-black-screen-of-death/80977#80977 and also http://superuser.com/questions/88904/why-does-my-windows-7-boot-up-to-a-black-screen-after-login/89092#89092 just to point to a couple.

This happened to me also where Win7 incorrectly identified my video card and installed the wrong driver. The majority of instances I've heard of (though not all) also had the issue being an incompatible or incorrect video driver. In other cases it was another device driver that was either not really Win7 compatible or incorrectly identified.

share|improve this answer
    
These are both different than my problem. The first has a mouse cursor still showing which mine does not. The second can get explorer to come up using task manager which I cannot. I can solve my problem by cycling the power on the box. Safe mode is not necessary and sometimes I don't even have to cycle the power, it just comes back after a while. –  Leigh Riffel Mar 12 '10 at 21:21

We have a Windows 7 Thinkpad X200 tablet that does this all the time too. We updated the Lenovo power manager and a few other drivers and tweaked the power settings a bit. We did have a Corsair SSD in it. Does your system match any of these variables?

share|improve this answer
    
No matches. SATA not SSD, Dell not Lenovo, Desktop not Tablet, One drive Not Multiple. Thanks for checking. –  Leigh Riffel Mar 12 '10 at 20:33

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.