Stop 0xC2 or BAD_POOL_CALLER

The Stop 0xC2 message indicates that a kernel-mode process or driver incorrectly attempted to perform memory operations in the following ways:

By allocating a memory pool size of zero bytes.
By allocating a memory pool that does not exist.
By attempting to free a memory pool that is already free.
By allocating or freeing a memory pool at an IRQL that was too high.

This Stop message is typically due to a faulty driver or software.

Interpreting the Message

Table C.5 describes the information provided by Stop 0xC2 messages. The value of the first parameter indicates the type of violation (see the Description column) and determines the meaning of the next three parameters.

Table C.5 Parameter Listing for Stop Message 0xC2

Parameter 1	Parameter 2	Parameter 3	Parameter 4	Description
0x00000000	This value is always 0	The pool type being allocated	The pool tag being used	The caller is requesting a zero byte pool allocation
0x00000001, 0x00000002, or 0x00000004	Pointer to pool header	First part of pool header contents	This value is always zero	Pool header has been corrupted
0x00000006	Reserved	Pointer to pool header	Pool header contents	Attempt to free a memory pool that was already freed
0x00000007	Reserved	Pointer to pool header	This value is always zero	Attempt to free a memory pool that was already freed
0x00000008	Current IRQL	Pool type	Size of allocation	Attempt to allocate pool at invalid IRQL
0x00000009	Current IRQL	Pool type	Address of pool	Attempt to free pool at invalid IRQL
0x00000040	Starting address	Start of system address space	This value is always zero	Attempt to free usermode address to kernel pool
0x00000041	Starting address	Physical page frame	Highest physical page frame	Attempt to free a non-allocated nonpaged pool address
0x00000042 or 0x00000043	Address being freed	This value is always zero	This value is always zero	Attempt to free a virtual address that was never in any pool
0x00000050	Starting address	Start offset in pages from beginning of paged pool	Size in bytes of paged pool	Attempt to free a non-allocated paged pool address
0x00000099	Address being freed	This value is always zero	This value is always zero	Attempt to free pool with invalid address or corruption in pool header
0x0000009A	Pool type	Size of allocation in bytes	Allocation's pool tag	Attempt to allocate must-succeed

Resolving the Problem

The following suggestions are specific to Stop 0xC2 errors. For additional troubleshooting suggestions that apply to all Stop errors, see "Stop Message Checklist" later in this appendix.

A Stop 0xC2 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, DVD playback, and CD mastering tools.
A Stop 0xC2 message might also be due to failing or defective hardware. If a Stop message points to a category of devices (such as disk controllers, for example), try removing or replacing the hardware to determine if it is causing the problem.
If you encounter a Stop 0xC2 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 0xC2 messages, see the Microsoft Knowledge Base link on the Web Resources page at http://www.microsoft.com/windows/reskits/webresources. Search using keywords winnt, 0x000000C2, and 0xC2.