How to Fix irql_less_than_or_equal Errors Caused by Poorly Written Drivers: Glary Boot Defrag Driver

While doing regular maintenance and software updating on my system one day, I ran into a situation where I saw quite a few reboots and blue screens.

What had happened? I could not be sure, but the Windows blue screen stated that it was an irql_less_than_or_equal error, or a driver error.

To fix this, follow a few steps:

  • Find the offending driver with Nirsoft Blue Screen Viewer.
  • Check if the driver is still installed using Driverquery.

In my case, it was BootDefragDriver.Sys from Glary Utilities that was causing the problem. As I use an SSD and don’t wish to do a boot time defrag, I simply deleted the driver and disabled any Glary boot time startups or optimization. It looks like others have had the issue, which has since been fixed, but I still prefer to disable and delete this feature.