won't shut down: "acpi_power_off called"

[Mike Chandler <mailmanmike@sbcglobal.net>]

Debian testing, kernel-2.6.3-1-686-smp, pentium 4, @3.0Ghz--
When I go to turn off the machine, it goes through all the screen messages as 
usual, but won't turn off. (Need to hold in power switch for 5 seconds to 
turn off.)
The last two lines of messages are here:

Power down.
acpi_power_off called

It has a American megatrends bios,
and the settings are like this:

ACPI Standby state - auto	
Power Management/APM - enabled

I have googled for this and came up with the problem, but no solution.
Thanks!