1. Click Start, and then click Shut Down.
2. Select Restart, and then click OK.
3. Press F8 (several times) at the indicated time: 

• For an x86-based computer: When a screen of text appears and then disappears (the screen of text may include a memory test, lines about the BIOS, and other lines), press F8. There may be a prompt that tells you when to press F8.

• For an Itanium architecture-based computer: After making your selection from the boot menu, press F8. There may be a prompt that tells you when to press F8.

4. Use the arrow keys to select Last Known Good Configuration, and then press ENTER.
5. Use the arrow keys to highlight an operating system, and then press ENTER.

Note: Choosing the Last Known Good Configuration startup option provides a way to recover from problems such as a newly added driver that may be incorrect for your hardware. It does not solve problems caused by corrupted or missing drivers or files.