If you have an AMD processor and are considering upgrading to Windows Service Pack 3 (SP3), then it is important that you apply this patch before SP3. Otherwise, your system may possibly get stuck in a loop of reboots that will stop Windows XP from starting.
On a technical level, there is a problem with the way that the System Preparation (Sysprep) image is created. According to one explanation offered by Microsoft "The problem may occur if the original Sysprep image for Windows XP Service Pack 1 (SP1), for Windows XP SP2, or for Windows XP SP3 is created on a computer that uses an Intel processor and is then deployed on a computer that does not use an Intel processor. In this configuration, the Intel processor driver (Intelppm.sys) may try to load after the computer is upgraded to Windows XP SP2 or to Windows XP SP3. The driver does this because an orphaned registry key remains from the original Sysprep image." In these cases you may also see the following error messages:
A problem has been detected and Windows has been shut down to prevent damage to your computer...
Technical information:
STOP: 0x0000007E (0xC0000005, [number1], [number2], [number3])
SYSTEM_THREAD_EXCEPTION_NOT_HANDLED
When Physical Address Extensions (PAE) is enabled, you may receive the following error message: STOP 0x000000FC (ATTEMPTED_EXECUTE_OF_NOEXECUTE_MEMORY)
[number1], [number2] and [number3] listed above will be random, alphanumeric and 10 digits long. However, 0x0000007E and 0xC0000005 will always be present for this type of error. Note 0x0000007E errors have multiple causes, but if it is an AMD processor and you have just installed SP3, there is a good bet that this patch will fix the issue. Ideally the patch should be applied before the Windows XP Service Pack 3.