The online system should be used for guidance only. So does the phone system with your status. USCIS servers sometimes are down or, after your case is approved, your information is populating in all all federal databases. As has been advised elsewhere on this site, please do not panic when validation errors occur, or invalid case number errors occur...just as the sun will rise tomorrow in the east, after a few days, all will be back to normal.
@sunny89, please do not supply wrong information to people, esp. if you are not sure. While you say you have never heard of the validation errors, us who have been working with USCIS for 12+ years, have heard about it a million times, have personally experienced it, and we know that it is normal. Good luck.