command in Windows 2000 is not available on desktop computers without a battery, even if Advanced Power Management (APM) is correctly configured in the computer's BIOS and enabled in Windows 2000.
The Standby feature is available only on APM-compliant computers that have batteries as an optional power source.
This behavior is by design
The standby vector in Ntapm.sys is disabled on any computer that does not have a battery. APM on many desktop computers does not support this feature. However, the hibernate power-off and shutdown power-off features work. Standby is available on Advanced Configuration and Power Interface (ACPI) desktop computers.