<form id="Form1" action="transform.aspx?ProdName=Windows+Operating+System&ProdVer=5.1.2600.5512&EvtID=5&EvtSrc=ACPI&FileVer=5.1.2600.5512&FileName=acpi.sys&EvtType=Error&LCID=" enctype="application/x-www-form-urlencoded" method="post"> I am having this same error come up. I got the thread from someone else online who is having the same issue. Its crashing my machine fatal errors and microsoft doesnt know what this is??????HELP Details Product: Windows Operating System ID: 5 Source: ACPI Version: 5.2 Symbolic Name: ACPI_ERR_AMLI_ILLEGAL_IO_WRITE_FATAL Message: %2: ACPI BIOS is attempting to write to an illegal IO port address (%3), which lies in the %4 protected address range. This could lead to system instability. Please contact your system vendor for technical assistance. Explanation The system BIOS attempted to incorrectly access hardware resources concurrently with the operating system. This type of access cannot be synchronized and can cause system instability. User Action Contact the system vendor for an updated BIOS and follow the vendor's instructions for installation. Currently there are no Microsoft Knowledge Base articles available for this specific error or event message. For information about other support options you can use to find answers online, see http://support.microsoft.com/default.aspx. </form> 1 person needs an answerI do too

The BIOS is "misbehaving". As the instructions indicate, check for and install an updated BIOS. If no such BIOS exists, contact the system/motherboard maker.