BT have cottoned on that using admin for a password is a dumb idea. So they are updating their routers' firmware to use the serial number as default password. It will do this even if you have changed your router's password.
Some HomeHubs updated today, and you will wind up having to enter the new password, and change it obviously.
You may also have to set up your wireless and your hub phone again.
Also any applications that had ports forwarded may get erased from the router memory, and have to be set up again from scratch.
All credit to this heads up goes to Jitendar Canth on DVD Reviewer. I am just spreading the love.