Se você não conseguir fazer logon na máquina com o novo passe, tente usar KON-BOOT e altere a senha para a que deseja.
KON-BOOT , ele ignora todas as verificações de senha do Windows, para que você possa inicializar o Windows e alterar o senha. É como um live cd que inicializa antes do Windows e o engana quando solicitado pela senha.
Ótima ferramenta para hackear sua própria caixa (você só pode alterar o passe, não pode ver o antigo)
Do site:
Kon-Boot is an prototype piece of software which allows to change contents of a linux kernel (and now Windows kernel also!!!) on the fly (while booting).
In the current compilation state it allows to log into a linux system as 'root' user without typing the correct password or to elevate privileges from current user to root. For Windows systems it allows to enter any password protected profile without any knowledge of the password.
It was acctually started as silly project of mine, which was born from my never-ending memory problems :) Secondly it was mainly created for Ubuntu, later i have made few add-ons to cover some other linux distributions.
Finally, please consider this is my first linux project so far :)
Entire Kon-Boot was written in pure x86 assembly, using old grandpa-geezer TASM 4.0.