Chances are its a simple mistake like the time and date is incorrect, i have had this problem on several other computers i have seen. Best thing to do is...
Boot into Safe Mode when the computer gets passed the Bios press F8
Boot into safe mode, the computer should boot up as normal asking which account you would like
to login to [USERS] or Admin
Login to the user as your normally would, check the date is correct if not adjust accordingly.