Your event log contains:

Source: ACPI
Category: None
Type: Error
Event ID: 12
User: N/A
Computer: <ComputerName>
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 (0xXXXX - 0xYYYY). 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

If the Advanced Configuration and Power Interface (ACPI) BIOS creates memory address ranges that conflict with the memory ranges that the BIOS reserved for the operating system, you will receive this error message.

To resolve this issue, contact your BIOS manufacturer for a BIOS update.