Ok. So to debug this, please follow instructions:
Download your shop onto hardDrive (direcotries: modules, classes, controllers, overrides mainly). Do not download pictures.
Perform a test search for message "Approval failed" and locate which file is emitting this error.
Come back, and report.
Just a guess, but this may be some 3rd party module or modification integrated as override etc. Maybe some kind of CAPTCHA?
Some modules can modify core controllers and classes by preg replaces.