My monitor shows part (or sometimes the whole screen) very blurry while sometimes it's shaking rapidly, and I am be able to fix it only by restarting the machine.

Although I can't really reproduce the exact timing of this behavior, I think it happens when I try to play streaming media, but again, I'm not sure.

I hope someone has experienced this behavior before or anyone that can help me to get the problem and solve it.

System details:

  • Windows 7 x64
  • nVidia GeForce 8400 GS

Update I now find this error in the Event Log:

Display driver nvlddmkm stopped responding and has successfully recovered.

Update 2
Sometimes, the screen flickers and instead of getting blurred out, it just recovers. I then see this message: enter image description here

Important I would like to emphasize that this computer is not new and these problems are new and never happened before.

I cannot tell if it points to my error at all.

What is weird, that I tried to take a snapshot by using PrtScn, but it didn't print the messed up image, but a good image, which means it's something in the display.

  • 1
    You hit the nail on the head: First, I would try a different display, then go from there.
    – KCotreau
    Jun 6, 2011 at 23:00
  • @Mehrdad, which basically makes trying another display pointless, since restarting the computer solves the issue. Jun 7, 2011 at 8:16
  • As @LeeThibodeaux stated the first thing to do is update your drivers, the latest for your card is 275.33: nvidia.co.uk/object/… I remember there being a problem driver that caused overheating that got released via Windows Update some time ago but I thought that was a 195.xx driver... updating the drivers fixed the problem generally. This may have affected other drivers but could be circumstantial: google.co.uk/…
    – Mokubai
    Jun 9, 2011 at 7:27
  • I've installed the latest driver and the problem still occurs :( Jun 9, 2011 at 16:11

3 Answers 3


The display driver dying (nvlddmkm in your error log) and the visual display problems point the the card itself having some kind of problem, at least that's where it points to me.

But apparently someone else has had similar problems and dedicated a wesite to fixing it with various levels of success: http://www.nvlddmkm.com/

Personally I think that your graphics card is struggling with Windows 7s Aero desktop and the streaming video is pushing it over the edge, either the card is not switching overclocking modes well enough, is overheating, has some weird issue, or it has a hardware fault. Online errors for nvlddmkm point at it being fine on WinXP but problematic on Vista and above which to me suggests that the extra graphical strain is what is causing the problem.

Googling the nVidia GeForce 8400 GS tells me it is a 256MB card, and it may well be that Aero and streaming video is making the card run out of video memory, and that condition isn't being handled very well by the drivers. On my 1600*1050 display Aero (on Vista) is using 137MB of VRAM with several windows open, and streaming video (if decoded by the graphics card) would use a significant amount more. You can check out video memory usage using GPU-z and checking the "sensors" tab (make sure to also click the box that says "Continue refreshing while in background" at the bottom as well) and then doing the king of things that you would noramlly be doing. If your computer has problems once you get near to, or exceed 256MB then that's likely to be your problem.

As a minimum I would check your drivers as LeeThibodeaux said, and then consider upgrading to a low-end current generation graphics card with 512MB or more VRAM.

  • As in my updated answer, I didn't have trouble untile recently. Maybe due to an update? What can it be? Jun 8, 2011 at 23:24

Are you on a desktop or laptop? If desktop make sure the cable is properly inserted into the video card. Make sure that all the pins are there (on the cable) and that none of them are moving. I had a similar problem because one of the pins was moving and didn't connect properly.

  • It's a desktop, the card is PCI-E. It's surely not a connection problem, cuz rebooting always solves the problem, I've updated my question, please take a look. Jun 9, 2011 at 16:19

Make sure you have the latest 64-bit drivers for your 8400 GS:


  • I have installed the latest driver and the problem still occurs :( Take a look at my question, I've added some content to it. Thanks. Jun 9, 2011 at 16:18

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