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.