Unable to add patient
Please make a backup of your database before doing anything.
Sometimes after entering a new patient's data and clicking to prompt a save, the error message UNABLE TO ADD PATIENT is displayed.
If none of that helps then I would do some experiments with database files. If the database file is stored on the server, copy it to the desktop and try working with it from there. You'll have to change your current database. If everything works fine then you know it's a file/network permission issue on the server.
Another thing to experiment with is to enter patient data into a new/blank database. This will help you determine if it's possibly a problem with your current database.