The display message, that appears as "IRQL_NOT_LESS_OR_EQUAL," represents an error that indicates a memory address triggering an unauthorized access. This error normally occurs after the installation of a faulty device driver, basic input/output system, abbreviated as BIOS, or system service on the computer.
Every computer program uses a pointer in order to refer to a specific part of memory. In turn, that pointer contains coded values that point toward a memory location. The error occurs when the code values are incorrect or corrupted. This forces the program to access an unproved memory portion, which triggers the error.
The error message, "IRQL_NOT_LESS_OR_EQUAL," can also appear during an installation of Windows. In that case, a user can fix the problem by verifying that all peripherals are compatible with that particular version of Windows.