What we think we know can sometimes get us into trouble. And the situation gets worse when we research the matter and we're still convinced we're right.
I don't make any claims to infallibility, but usually, if I'm convinced I'm right about something, you need to produce facts to prove me wrong. This attitude tripped me up during a recent system upgrade. After I completed the OS upgrade, I had problems with hibernation, which I didn't think would be a concern with an Advanced Configuration and Power Interface (ACPI)-compliant system. The hibernation problem turned out to be a known bug with the Adobe Type Manager 4.0 driver, but while trying to diagnose the problem, I got sidetracked by the ACPI versus Advanced Power Management (APM) question for system power management.
I was sure that the system was ACPI-compliant. Every time I've booted this computer during the past 2 years, the screen has flashed the ACPI BIOS boot message, so I was certain that I was running the ACPI-compliant hardware abstraction layer (HAL). After a visit to the system vendor's Web site, I discovered that I was a few generations behind in system BIOS updates (I was running A04, the current version was A14, and the oldest version still on the vendor's Web site was A08). Upgrading the system BIOS didn't affect the hibernation problems, but the discovery was interesting nonetheless.
The next step in my diagnostic process was a clean install of the OS into a scratch partition on one of the system hard disks. The installation went smoothly and didn't exhibit the power management problems that the other OS installation had. Now I was more confused. A drilldown with the Device Manager application identified the problem. The new installation, performed after the BIOS upgrade, showed the ACPI information under System devices. The original upgraded installation didn't have the ACPI information present. A call to Microsoft confirmed my new suspicion: Microsoft had tightened the requirements for an ACPI-compliant BIOS. The BIOS I'd been running since Windows NT 4.0 wasn't compliant for newer OSs. If I hadn't seen the ACPI BIOS message so often, I probably would have checked for ACPI compliance sooner, but I let my complacency about what I thought was right guide my actions. If I'd checked Device Manager sooner, I could have saved some diagnostic time.