Well I didn't get very far with that. It appears the browser autofill is causing the problem. On loading the profile page the password box is being filled in automatically - row of dots. This is causing any update to fail as they are leaving the password in. This is what I have done to correct this.
Ditched altering the language file as that was causing a problem with the login form.
Altered the user_databform.html file - password part to read like this ...
(Fill in only if you
change your password)
If you notice I have added autocomplete="off" to the password input. This stops the browsers adding a stored password. I have also removed the madatory asterix from both the Password and Repeat Password text. There is warning text now too below the bold Password text.
Just tried it out on the person that is having problems and she seems to be ok now.