What does it fix?
Reinstall Windows 8 upgrade driver.

Update VAIO user guide.
1. Exit all running programs.
2. Download this update and save it to your hard drive.
3. When the download is completed, locate the downloaded file inthe location you specified.
4. Double-click EP0000310145.exe to run it.
5. Wait while the wizard updates your software.
6. When the installation is complete, restart the VAIO.