Troubleshooting: DRIVER_IRQL_NOT LESS OR EQUAL (kbdclass.sys) Error in Windows PC

  • Some PC users have an unusual problem with wireless keyboards, especially Microsoft wireless keyboards.
  • When they plug in a standard wired USB keyboard, they can use their Windows 10 PC, but as soon as the wireless keyboard is plugged in and they press a key on the keyboard, the PC hangs and displays a blue screen of death with the error DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys).

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The DRIVER_IRQL_NOT_LESS_OR_EQUAL error (kbdclass.sys) is being reported, how can it be fixed?

The code based on a class that has been altered or corrupted crashes when it is a system file, with a .sys extension. As a result, you will see the KBDCLASS.SYS error if something has been changed within the class, or if something has not been changed, which causes other programs to fail or stop working properly when they start up or run.

Several days ago, I bought a new USB keyboard and mouse. After plugging them in, I clicked the keyboard and got a BSOD. In it, it says DRIVER_IRQL_NOT_LESS_OR_EQUAL because the ‘kbdclass.sys’ driver was malfunctioning. After updating all my drivers, it stopped working until I restarted Windows 8. When the system logs in, the same BSOD appears regardless of what key I press on the keyboard, and Windows restarts. I would appreciate any assistance you can provide.

Some PC users have an unusual problem with wireless keyboards, especially Microsoft wireless keyboards. When they plug in a standard wired USB keyboard, they can use their Windows 10 PC, but as soon as the wireless keyboard is plugged in and they press a key on the keyboard, the PC hangs and displays a blue screen of death with the error DRIVER IRQL NOT LESS OR EQUAL (kbdclass.sys). In this post you will find the best solutions to this problem.

What causes the “DRIVER_IRQL_NOT LESS OR EQUAL” error message?

You may not experience problems with Windows classes if they aren’t a system file. However, in this particular case we are talking about .sys files, which are system files. In this case, KBDCLASS.SYS crashes as a result of a change in the code, causing BSODs and other issues.

Thanks for the detailed description of the issue and your question. To begin with, let us explain what KBDCLASS.SYS is. In fact, it is a Keyboard Class that is classified as a driver, so it is at the heart of the problem. As KBDCLASS.SYS handles all combinations of keys you click on, each separate click on keyboard keys, it handles all of them.

After using the laptop with its integrated keyboard for the first time, I encountered a strange problem. Every few minutes to half an hour, Windows crashes with a BSOD containing the code DRIVER_IRQL_NOT_LESS_OR_EQUAL while typing on the integrated keyboard. As soon as I plugged the external keyboard in, I tried typing on it for a few hours without any problems. However, I returned to the integrated keyboard and the same error occurred again after some minutes.

I’ve got a new Acer Aspire Core 2 Duo 1.66 GZ with 1GB RAM and a Nvidia GeForce Go 7300 graphics card. I bought a MSI Mega Sky 580 USB Digital TV tuner for it that includes a basic remote control. Twice when using the remote the system has blue screened and re-booted. When I don’t use the remote, I don’t seem to have any problems. I was asked to run Memtest86 to check the ram – 8 passes reported no errors. Chkdsk also came back with no problems. I think the problem may lie with the tv tuner driver – bdacap.sys.

I had no problems after reinstalling Windows 10 Pro up until I installed Webroot, then I got a blue screen of death whenever I pressed a key on my Microsoft Wireless 5000 keyboard. It works with a wired mouse and keyboard but is not compatible. I have been using this system without problems for over 2 years now. Could someone tell me what the problem is or if there is a fix? I appreciate your help.

This occurs when the class code is corrupted or changed, and the class is a system file with a .sys extension, so all code dependent on it becomes stuck. Consequently, you will see a KBDCLASS.SYS error if there has been a change or omission in the class, which leads to other critical startup or runtime programs failing to launch.

Webroot antivirus is found to be at the heart of the BSOD DRIVER_IRQL_NOT_LESS_OR_EQUAL error (kbdclass.sys). Webroot has been informed of this issue, and has created a patch. Therefore, visit Webroot’s official website and check for the patch. The issue arises because of a conflict between keyboard class and Webroot software.

It’s not often that a BSOD will tell me which driver is responsible, so I need to investigate the issue. Kbdclass.sys is a Microsoft driver, so it’s probably caused by another driver.

Webroot Antivirus is usually the cause of this problem, but the following methods can be used to rule out other causes.

How to fix ‘DRIVER_IRQL_NOT LESS OR EQUAL’?



Updated: February 2024

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Reinstall the USB controllers

  1. The Device Manager can be accessed by pressing WINDOWS + X.
  2. In the Device Manager window, double-click the Universal Serial BUS Controllers option.
  3. Select Uninstall Device from the submenu after right-clicking the Generic USB Hub option.
  4. Make sure that each USB root hub on the same list is followed in the same manner.
  5. Afterward, restart your computer and the controllers will be automatically reinstalled.

Updating the driver

  1. In the pop-up menu, click “Device Manager” after pressing WINDOWS + X.
  2. In the Device Manager window, expand the Keyboard option.
  3. In the list of keyboard drivers, right-click on the name of the device listed and select Update Driver from the submenu.
  4. You can now remove the older version of the drivers (if available) by clicking the first option on the next screen “Automatically check for updated drivers”.
  5. You will be guided through the rest of the process based on the instructions on the screen.

Resetting the keyboard driver

  1. In the pop-up menu, click “Device Manager” after pressing WINDOWS + X.
  2. Locate and double-click the “Human Interface Devices” option in the “Device Manager” window.
  3. Choose the “Properties” submenu from the right-click menu when you locate the HID keyboard driver here.
  4. The vertical menu at the top of the Properties window contains a Driver tab.
  5. Then click OK on Reset Drivers in the same menu.



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Frequently Asked Questions

SYS files such as kbdclass.sys are classified as Win32 EXE (driver) files. As a keyboard class driver file, it was created by Microsoft for use in the Microsoft Windows operating system. Kbdclass.sys was first released 2006-08-11 with Windows Vista for the Windows Vista operating system.

IRQL_NOT_LESS_OR_EQUAL (sometimes simply called "IRQL") is a typical memory-related error that occurs when a system process or device driver attempts to access a memory address for which it does not have valid access rights.

The error check DRIVER_IRQL_NOT_LESS_OR_EQUAL has the value 0x0000D1. This indicates that the kernel-mode driver was trying to access paging memory when the process's IRQL was too high.

  1. Start Windows
  2. Press the Windows key and the C key to open the Quick Access Toolbar.
  3. Click on Settings.
  4. Go to Change PC Settings.
  5. Select General.
  6. Click the Advanced Startup button
  7. Click Restart Now
  8. Go to Troubleshooting
  9. Select Advanced Settings
  10. Click on UEFI Firmware Settings
  11. Select Restart

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Mark Ginter is a tech blogger with a passion for all things gadgets and gizmos. A self-proclaimed "geek", Mark has been blogging about technology for over 15 years. His blog, techquack.com, covers a wide range of topics including new product releases, industry news, and tips and tricks for getting the most out of your devices. If you're looking for someone who can keep you up-to-date with all the latest tech news and developments, then be sure to follow him over at Microsoft.