You should reset the BIOS to the setup defaults.

Follow this procedure:

1. Ensure the computer is turned off.
2. Turn on the computer.
3. At the SONY screen, press the F2 key.

IMPORTANT: If the SONY screen does not appear, press the F2 key within 7-10 seconds after turning on the computer.

4. In the AwardBIOS Setup Utility window, press the RIGHT ARROW key until the Exit menu is selected.
5. On the Exit menu, press the DOWN ARROW key until Load Setup Defaults is selected.
6. Press the ENTER key.
7. In the Setup Confirmation dialog box, press the ENTER key.
8. In the AwardBIOS Setup Utility window, on the Exit menu, press the UP ARROW key until Exit Saving Changes is selected.
9. Press the ENTER key.
10. In the Setup Confirmation dialog box, press the ENTER key.

Source: sony.com