Each time a user attempts to login to the site for the first time ..the error Unable to save user. Please ensure your username is not taken and that your passwords match. is shown. There is no user by this name and the passwords do match..
Any assistance greatly appreciated.
Is the user's account actually created and they are registered, or is no registration taking place either? If you try to log back in afterwards, does that work?
I've never heard of this issue before, so a little more info will help. We'll help get you going though.