Once you have pressed the Power button on your computer, press the F8 key again and again. The windows Advanced options screen, such as the start window normally, will appear. From there, select safe mode with the up arrow key. Then hit enter.
A window will pop up in a safe mode and you will be asked yes (or) no. To perform a system restore, select no. Then select Start / All program / Accessories / system tools / system restore. Select Restore my computer to an earlier time. Then go to Next and Next. The machine will restart and you will be fine.