Read from these and use which you like.
http://www.google.com/search?hl=en&q=VISTA+SYSTEM+RESTORE&btnG=Google+Search&aq=f&oq=
My Toshiba Satellite laptop with Vista (purchased a couple of months ago) will not fully boot up after having installed Quicktime yesterday (I powered down sometime last night. After the splash screen, the screen comes up where, normally, the user login is displayed, but the "Please wait" of death keeps me waiting indefinitely and the login field never shows. If there is already a thread on this please point me in the right direction. Thanks.