If, like me, you have set up a movable type install with one author and have given the author permissions to the customer, who subsequently changes the password. The customer uses auto save for his passwords, and buys a new machine and throws the old one out.
If like me you panic and can't find a way of recovering the password, the movable type support pages direct you to MT-Medic. MT-Medic allows you to do some useful or emergency tasks on your MovableType installation.