Windows stopped with a DRIVER_IRQL_NOT_LESS_OR_EQUAL (bug check 0x000000D1) because a kernel-mode driver attempted to access pageable memory at an interrupt request level (IRQL) that was too high. This is similar to IRQL_NOT_LESS_OR_EQUAL (0x0A) but specifically implicates a driver rather than the kernel itself. The offending driver is usually named on the blue screen or in the crash dump.
A kernel-mode device driver (network adapter, GPU, storage, Bluetooth, audio) accessed pageable memory while executing at DISPATCH_LEVEL or above — a driver coding error.
A driver used a freed or NULL pointer while running at an elevated IRQL.
The driver called a function in another driver that was subsequently unloaded.
A recently installed or updated driver introduced a regression that triggers this memory access violation.
Faulty RAM causes unpredictable memory access errors that manifest as IRQL violations in driver code.
How to fix it
Note the driver filename shown on the blue screen (e.g., tcpip.sys, netio.sys, nvlddmkm.sys). This is the most direct lead to the fix.
Update the driver identified on the blue screen. For GPU drivers, use Display Driver Uninstaller (DDU) in Safe Mode then reinstall the latest version.
If the crash started after a driver update, roll back the driver: Device Manager > right-click device > Properties > Driver tab > Roll Back Driver.
Run Windows Memory Diagnostic (mdsched.exe) or MemTest86 to check for faulty RAM, which can cause corrupted pointers that trigger this error.
Run `sfc /scannow` and `DISM /Online /Cleanup-Image /RestoreHealth` in an elevated Command Prompt.
Enable Driver Verifier (`verifier.exe`) to stress-test all non-Microsoft drivers and force a more informative crash dump identifying the exact faulty driver.
If the offending driver is for a network adapter, try updating or replacing the network adapter driver, or temporarily disabling the adapter to confirm it as the source.
