Remove all floppy disks, CDs, and DVDs from your computer, and then restart your computer.
Click the Start button , click the arrow next to the Shut Down button , and then click Restart.
Do one of the following:
If your computer has a single operating system installed, press and hold the F8 key as your computer restarts. You need to press F8 before the Windows logo appears. If the Windows logo appears, you'll need to try again by waiting until the Windows logon prompt appears, and then shutting down and restarting your computer.
If your computer has more than one operating system, use the arrow keys to highlight the operating system you want to start in safe mode, and then press F8