The ACPI drivers on your computer control the power management of your Windows 7 or Vista system. When you are experiencing data loss or strange sounds coming from your computer's tower, your ACPI drivers might be out of date. Updating these drivers is not very hard when you use the software that came with your Windows 7 system. The Windows Update software will automatically update your ACPI drivers by accessing Microsoft's database.
Click the "Start" button and go to the "Windows Update" icon.
Click on the "Check for updates" button on the left side of the panel.
Wait for the computer to check for the updates, then click on the "ACPI Drivers" update or the "Microsoft Update" from the menu.
Click the "Install Updates" button on the bottom of the screen.
Restart your system after the updates have been installed.