This one gives you full read/write access, and admin access. It does not work on Windows 2000 anymore.
So, you sit and stare at the login prompt for a while, and the screen saver will come up. Here comes our attack. We replace the screensaver with a different program which will not ask for a password.
Usually you can log in with a guest or regular user account. Do that and go to the directory \Windows\System32 and replace the login screensaver with the command line prompt.
cd \Windows\System32
ren logon.scr login.bak
copy cmd.exe logon.scr
To save time, you might want to change the time out in the registry from 900 seconds to something shorter, but that goes to far in an epinion. (search under \HKEY_USERS\DEFAULT)
Then reboot, and just wait for the screensaver to come up. It will be the command line prompt and you'll have access to the computer. Full access! You can run the user manager, create a new account and give it admin privileges or just change the admin password...
Also don't forget to restore the original screen saver.
