NDIS.sys Blue Screen of Death IRQL_LESS_OR_NOT_EQUAL on Windows 7


About a year ago, my friend had a problem with his laptop where out of nowhere it decided to start throwing a “Blue Screen of Death” (BSOD). This happened upon every boot, around when the login screen said “welcome”.

The bluescreen’s error text read IRQL_LESS_OR_NOT_EQUAL. For your information – this generally is a driver problem. The driver in question was NDIS.sys.

After searching around, I tracked down that the problem was with the Atheros Wireless card in his laptop. I temporarily fixed the problem here by booting into Safe Mode and disabling his wireless card and ethernet card. The system now boots and works, but no networking. No good! I found that the ethernet card could be re-enabled with no further issues.

Now, down to the interesting part – fixing the problem. After about a week, through trial and error, I found a solution.

How to fix NDIS.sys BlueScreen of Death on Windows 7

NOTE: You might need to check below under the “Update” section, if my instructions don’t help.

  1. Boot yourself into Safe Mode. Make sure you DON’T boot into Safe Mode with Networking. You will crash into another BSOD.
    1. To boot into Safe Mode, power on the computer and wait for the BIOS splash to disappear. This usually displays your PCs Brand Logo. Then, press F8 repeatedly, lifting about once every second.You should see a black screen with white text and a list of options. Use the Arrow Keys to select Safe Mode and press Enter. You can safely ignore the list of drivers that appear as the computer boots.
  2. Once logged in, open up Device Manager, by searching “Device Manager” in the start menu.
  3. Open the Network Adapters category in Device Manager. Search for the Atheros device in the list. Double-click the adapter.
  4. In the Properties window, choose the “Driver” tab and then choose “Update Driver”
  5. In this popup, choose the “Browse my computer for driver software” option.
  6. On the next page, choose “Let me pick from a list of device drivers on my computer. Ignore the browse field, it’s not important.
  7. You should see a list of two drivers, with identical names except for brackets. The first one says (Microsoft) and the second says (Atheros).
    1. The problem is Microsoft’s driver for this device causes a BlueScreen.
    2. Choose Atheros’s driver and Click next.
  8. Wait for it to install.
  9. Once successfully installed, simply click close.

Close the Properties window, Close Device Manager and reboot your computer as you would normally (not Safe Mode).

If all has gone well, you should be able to boot up and use your WiFi absolutely fine!

Hope I helped!


A couple of people have commented saying this didn’t help them. Thanks to Ian E for his comment below on an alternative fix, using some of the above information. He used Safe Mode to disable the driver, and downloaded the latest driver from the internet.

49 thoughts on “NDIS.sys Blue Screen of Death IRQL_LESS_OR_NOT_EQUAL on Windows 7”

  1. I’m just writing because I can get with this help of you, I did a bit different, I wasn’t starting windows, them I pulled the wifi card to start windows and i repair the system. Thanks for this text helpfull.

    1. Yeah, that also would work, but using safe mode is sometimes more convenient, as some laptops for example will have the WiFi card buried deep inside, and it’s inconvenient to disassemble the entire laptop to get to it 🙂

  2. Thanx tried the above method and it worked was about to restore to manufacture settings after several restore points failed to fix the problem. Thanx again.

  3. Whilst the above did not work for me it served as a useful pointer. Looking at the driver properties from within Safe Mode it was clear that the Atheros version was already installed but in this case the driver dated back to 2009 so I figured there’d be a more recent update. Disabling the Atheros adapter in Device Manager meant I could restart the machine normally and with a LAN connection providing Internet access I used Windows Update to search for an updated WLAN driver. WU duly found and installed one, reanabled the WLAN adapter and I was back wireless again. A reboot proved it was fixed (Packard-Bell Easynote laptop)

    1. Hi . So how do we get to know which update needs to be done for atheros adapter ? As soon as I enabled it my system crashed again 🙁 so I have a machine on which I can’t use internet .

    2. Good day all.

      A great thank you to Ian.

      Had a bit of a struggle with this one.

      Disabled the wireless device in safe mode and connected via cat5 cable and updated the drivers. All sorted.

  4. Thank you! That worked very well.
    Odd how that driver must have somehow changed from Atheros to Windows.
    I did some installation of Mcafee and then uninstalled that and put AVG back – much less hassle. I am guess Mcafee may have had something to do with it?
    Always a mystery. the “ghost” in the program.
    Thanks again. You rock.

    1. Yes, this is to fix the NDIS.SYS bluescreen. Classpnp.sys sounds related – as this BSOD is caused by a Network Driver.
      If your BSoD didn’t say NDIS.SYS was the problem, this probably won’t help you 🙂

    2. First of all you need to find out which driver is damaged, the to try to update it, just in case it’s out of date, if that doesn’t help, then you should try to disable that driver and install a new one with the same functions.
      I had the problem with my Network adapter, read the comment I wrote lower here, maybe it will help you.

    3. Thank you all, with help of you all I fix it.

      1.The first thing I do is I go in safe mode and disable atheros internet.

      2.Restart it and started normally, but without internet, I didn’t have cable which ian mentioned

      3.But I come across an idea to use my samsung mobile as internet

      4.i plug my phone in laptop with usb
      And then I go to settings on phone and enabled usb tethering, that way I had acces to internet

      5.Then I just opened windows update and update all my drivers

      And that way my problem solved

      I can’t believe that this blog from 2013 helped me.

  5. Hey, I would like to thank you for this text, it was helpful. But I did it a bit different, so I decided to write it here and maybe it could be helpful for someone else too.

    So, my blue screen said that I had a problem with ndis.sys and my laptop wanted to start up only in Safe Mode. So I downloaded Bluescreenview (from here http://www.fiberdownload.com/Transfer… ) which is used so you can see the files from minidumb folder. (when you open bluescreenview, once it’s downloaded, it will open the minidubm folder) That’s how I found out that the problem is with Atheros Wireless Network Adapter (which I didn’t know earlier) and that it’s installed in 2009. When I disabled it, my Windows started normally but there was no internet.
    Then I downloaded Driver Identifier (from here http://driveridentifier.com/ ), which is to identify all the compatible drivers from your computer, it told me that there’s an available Atheros WNA from 2013 for my laptop.
    I copied the name of the adapter, with whom I had problems, in the Google searching box and found the newest version here http://www.atheros.cz/ and downloaded it.
    Since it was a zipped file, I extracted it in a new folder.
    Then I went in the Device Manager in my Control Panel, clicked on my old Atheros adapter to open the Properties box, then Update adapter, and when it said where to find the Update, I Browsed for the folder with the files that I downloaded and extracted earlier. And that was it.
    It appeared a new icon from Atheros in the Device Manager and it was the right one, and the old one I left disabled.

  6. E machine website did not have updated driver. Followed lan e steps to get the updated one from windows updates. Thanks.

  7. Thanks Ian E – Your solution worked like a charm. Wondering though how all of a sudden Windows decided to crash…

  8. I’m having the same issue. I’ve tried the original solution, and Ian’s suggested variation, but no luck. With either the Atheros or Windows driver I get the blue screen when I enable it (or on boot if it’s already enabled).

    I’ve also tried Elena’s solution, but when I run Driver Identifier, it doesn’t find the Wireless driver, so I can’t get the new driver name. Might this be because the device is disabled? If I enable it, it crashes immediately…

    I’ve tried downloading a driver manually based on the name in device manager, but it won’t let me install it, as it says I’ve already got the latest installed.

    Any other ideas? Anyone else for whom these steps have not solved their problems?


    1. I actually managed to find a newer driver now (from 2014), and it installed it… However, as soon as it had finished, it crashed again 🙁

      Looking in BlueScreenView it seems the crash has changed a bit, but is still caused by athr.sys, though there’s a new file “halmacpi.dll” in between it and ndis.sys…

      1. Hmm, not too sure then. athr.sys definitely sounds like “Atheros”, so it does appear related.

        I might suggest just disabling the wireless adapter completely (using safe mode) and running Windows Update using an alternative connection (ethernet maybe?).
        You could also try running sfc /scannow in a Command Prompt (as administrator) to see if any Windows files are damaged.

  9. Hey just trying to do this and cosidering I do not have a lan cable will it work if I download the new updated driver from another computer onto a USB and stick it on in safe mode?

      1. Would you help me find a link to the right driver and do I need to save it to a specific place in safe mode? Tried it just now and it won’t find another driver and tells me it’s still the best one which is the 2009 one

        1. If you follow my instructions as above, you shouldn’t actually need to download a new driver, but just in case you do, you should look up the drivers for your specific desktop/laptop model, and look for the “Wireless” or “WLAN” drivers.

          When you download these, it’s likely to be an installer file (such as a .exe file) which will copy the new drivers for you. If you receive a message about Windows Installer and Safe Mode, then temporarily disable the device and reboot normally to run the installer.

          If instead you receive some .sys and .inf files, you should copy them to a memorable place on your computer (such as your desktop), then follow my instructions up to step 6 – but Browse instead. Once you click that, browse for the folder you placed these files and it should discover the new drivers. After you have continued through the wizard, you can remove those driver files from wherever you placed them (Windows makes a copy of them when the driver is installed).

          I’m sorry i can’t provide more specific instructions, but there are a wide variety of computers and network cards, and you need to find the one that’s just right for you. As above, your computer manufacturer’s support website is a good place to look.

  10. thanks. worked for me after a Windows 7 automated update on my desktop. it was actually an Intel network driver in this instance. loaded in safe mode disabled it. reloaded in normal mode (no blue screen). updated the driver and all fixed.

  11. You are a freaking godsend. This blue screen has driven me around the bend for 2 days, and with my workload centered on computer and internet, this was the simple solution I’ve searched for in the flood of the advices and everything else. Simple, and alost understated, but with the safe mode not being able to connect to internet, it wa the solution that undiputably worked the best (borrowed another laptop to download the required drivers).

    I was sceptical. Now I am a believer.

    Thanks again,


  12. Thanks. I just fixed a laptop on Windows 7 with this problem by following a very similar procedure:

    1-booting in safe mode,
    2-disabling the wireless driver in the device manager,
    4-downloading a newer version of the atheros driver for the same chipset (chipset is referenced on the name of the wireless interface in the device manager)
    5-unzipping the new driver
    6-manually installing the driver by pointing it to the new folder with the unzipped driver

  13. Thank you all, with help of you all I fix it.

    1.The first thing I do is I go in safe mode and disable atheros internet.

    2.Restart it and started normally, but without internet, I didn’t have cable which ian mentioned

    3.But I come across an idea to use my samsung mobile as internet

    4.i plug my phone in laptop with usb
    And then I go to settings on phone and enabled usb tethering, that way I had acces to internet

    5.Then I just opened windows update and update all my drivers

    And that way my problem solved

    I can’t believe that this blog from 2013 helped me.

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