Stop 0x0000000A or IRQL_NOT_LESS_OR_EQUAL

The Stop 0xA message indicates that a kernel-mode process or driver attempted to access a memory location to which it did not have permission, or at a kernel interrupt request level (IRQL) that was too high. A kernel-mode process can access only other processes that have an IRQL lower than, or equal to, its own. This Stop message is typically due to faulty or incompatible hardware or software.

Interpreting the Message

This Stop message has four parameters:

1. Memory address that was improperly referenced.
2. IRQL that was required to access the memory.
3. Type of access (0x00000000 = read operation, 0x00000001 = write operation).
4. Address of the instruction that attempted to reference memory specified in parameter 1.

If the last parameter is within the address range of a device driver used on your system, you can determine which device driver was running when the memory access occurred. You can typically determine the driver name by reading the line that begins with:

**Address 0xZZZZZZZZ has base at <address>- <driver name>

If the third parameter is the same as the first parameter, a special condition exists in which a system worker routine, carried out by a worker thread to handle background tasks known as work items, returned at a higher IRQL. In that case, some of the four parameters take on new meanings:

1. Address of the worker routine.
2. Kernel interrupt request level (IRQL).
3. Address of the worker routine.
4. Address of the work item.

Resolving the Problem

The following suggestions are specific to Stop 0xA errors. For additional troubleshooting suggestions that apply to all Stop errors, see "Stop Message Checklist" later in this appendix.

• A Stop 0xA message might occur after installing a faulty device driver, system service, or firmware. If a Stop message lists a driver by name, disable, remove, or roll back the driver to correct the problem. If disabling or removing drivers resolves the issues, contact the manufacturer about a possible update. Using updated software is especially important for multimedia applications, antivirus scanners, and CD mastering tools.
• A Stop 0xA message might also be due to failing or defective hardware. If a Stop message points to a category of devices (video or disk adapters, for example), try removing or replacing the hardware to determine if it is causing the problem.
• If you encounter a Stop 0xA message while upgrading to Windows XP Professional, the problem might be due to an incompatible driver, system service, virus scanner, or backup. To avoid problems while upgrading, simplify your hardware configuration and remove all third-party device drivers and system services (including virus scanners) prior to running setup. After you have successfully installed Windows XP Professional, contact the hardware manufacturer to obtain compatible updates. For more information about simplifying your system for troubleshooting purposes, see " Troubleshooting Concepts and Strategies" and "Troubleshooting Startup" in this book.

For more information about Stop 0xA messages, see the Microsoft Knowledge Base link on the Web Resources page at http://www.microsoft.com/windows/reskits/webresources. Search using keywords winnt, 0x0000000A, and 0xA.