Unable to alter or remove password.

> When I attempt to alter, remove or change my primary password under the users
> interface I receive an error that windows is unable to change the password.
>
> I can create a new user, create, alter and delete it's password.
>
> I have also noticed that I have a "switch user" button below my name when I
> start windows, or return when screen save is active and my user name is
> locked unless I use the "switch user" button.
>
> I have just also been locked out from logging on to the same computer as the
> only user visible was the primary user (mine) and that account was locked.
> The system finally let me on after I left the login screen for about 5 mins,
> it then accepted my password and let me log on.
>
> I have not altered any settings in passwords or administrative local security.
>
> Can someone suggest a solution?
>
> I have also discovered that I am unable to create a password disk as the
> password I have on my account is not recognized by windows.