I know how i can disable auto logon in windows 7 by using
netplwiz, but is there a way ( possibly a keyboard combination pressed during startup ) that will prevent autologon only for this one boot?
Hold down the shift key while the machine starts.
You may need a hotfix for this to work, support.microsoft.com/kb/977534
If you alternate right - left shift keys very quickly well Windows is booting it will bypass the auto log on and take you to a log on screen.