Your event log contains postings that are similar to:

<b>Source: ACPI
Category: None
Type: Error
Event ID: 12
User: N/A
Computer: Machine_Name
Description: AMLI: ACPI BIOS is attempting to create an illegal memory OpRegion,
             starting at address 0x400, with a length of 0x100. This region lies
             in the Operating system's protected memory address range (0x0 - 0x9fc00).
             This could lead to system instability. Please contact your system vendor
             for technical assistance. For more information, For more information,
             see Help and Support Center at: http://go.microsoft.com/fwlink/events.asp

Source: ACPI
Category: None
Type: Error
Event ID: 5
User: N/A
Computer: Machine_Name
Description: AMLI: ACPI BIOS is attempting to write to an illegal IO port address (0xcf8),
             which lies in the 0xcf8 - 0xcff 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

Source: ACPI
Category: None
Type: Error
Event ID: 4
User: N/A
Computer: Machine_Name
Description: AMLI: ACPI BIOS is attempting to read from an illegal IO port address (0xcfc),
             which lies in the 0xcf8 - 0xcff 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</b>
If you computer's BIOS tries to write to a port in ACPI Machine Language ( AML), you will receive similar errors. Windows NT-based computers, including Windows XP and Windows Server 2003, do NOT allow these operations as they can cause instability.

To resolve this problem, contact your manufacturer about a BIOS upgrade.