Hi gents,
This may a be a bit too techie for some, but on the other hand that's a solution you should have at hand for any occasion....
A couple of weeks ago my wife's Laptop locked her out (Windows XP). An error had occurred somewhere in the administrator password area, so there was little to be done as every solution would require us to, at least, have access to the operating system!
The answer came from an utility called Ultimate Boot CD for Windows:
http://www.ubcd4win.com/
This too comes as as iso image - means that you will need to burn it to a CD. And for that you may use the freeware InfraRecorder.
http://infrarecorder.org/
What does UBCD4WIN do? Is a "complete" operating system on a CD, packed with freeware utilities, that will let you perform almost any task you'd do if inside your own computer. Among other things it allows you to reset the Administrator password
So basically you'll need to download and burn the ISO on another PC, then insert the CD in the troubled one, maybe go to the Bios screen to tell the PC to boot from the CD and not from his Harddisk, and then perform the password change .... easier said than done
Even if you're not in trouble right now, consider having such a tool at hand!
Hope it helps!
Joao