ACPI

I am having the following entry in my System Log many times.
What is it and how do I eliminate it?

Event Type: Error
Event Source: ACPI
Event Category: None
Event ID: 5
Date: 6/12/2003
Time: 7:47:53 PM
User: N/A
Computer: MYSERVER
Description:
AMLI: ACPI BIOS is attempting to write to an illegal IO port address (0x90), which lies in the 0x90 – 0x91 protected address range. This could lead to system instability. Please contact your system vendor for technical assistance.

For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp.
Data:
0000: 00 00 00 00 04 00 52 00 ……R.
0008: 00 00 00 00 05 00 05 c0 …….?
0010: 00 00 00 00 00 00 00 00 ……..
0018: 00 00 00 00 00 00 00 00 ……..
0020: 00 00 00 00 00 00 00 00 ……..

Thanks for your help.