STOP: 0x00000020 (parameter, parameter, parameter, parameter) KERNEL_APC_PENDING_DURING_EXIT
This is a Windows 2000 Executive character-mode STOP message. It indicates that a kernel-mode asynchronous procedure call (APC) was found pending during thread termination. The first parameter is the address of the APC found pending during exit. The second parameter is the thread's APC disable count. And the third parameter is the current IRQL (interrupt request level). If the thread's disable count is non-zero, it is the source of the problem: the current IRQL should be 0. If it is not, a driver's cancellation routine returned at an elevated IRQL.
If this is the first time you have booted after installing new hardware, remove the hardware and boot again. Check the Microsoft Hardware Compatibility List to verify that the hardware and its drivers are compatible with Windows 2000. For information about the hardware, contact the supplier. If you are installing Windows 2000 for the first time, check the Windows 2000 system requirements, including the amount of RAM and disk space required to load the operating system. Also, check the Hardware Compatibility List to verify that the system can run Windows 2000. If Windows 2000 is loaded and no new hardware has been installed, reboot with recovery options set to create a dump file. If the message continues to appear, select the Last Known Good option when you reboot. If there is no Last Known Good configuration, try using the Emergency Repair Disk. If you do not have an Emergency Repair Disk, contact your technical support group.