I had a similar issue but mine kept referring to the email address. I later discovered that chrome automatically adds my username into the email field which comes up when you are check the save incomplete form box. 

All i did was check the save incomplete form box, delete the values entered into the email field and then uncheck the box. The form then submits. 

Am not sure its the same issue but you could just double-check. 

The problem only appears to happen if a field has been filled out incorrectly or a required field missed. The problem is that with tabs implemented the system has no idea how to take the user to the problem field. I would need a way to display which fields need to be reviewed or change tabs. Or possibly run a check each time the user changes a tab.