482447 Form not saving info sometimes 2

*** Must be experienced in PHP I am seeing a weird problem on a script I have, some accounts do not allow an item from a form to be saved when the check box is selected. Most accounts work as expected but some do not. I think maybe some accounts have invalid characters so I need this to operate correctly first then I want form validation on one script (no special characters, under a certain size, some fields numeric). I will bring that over to other sign up scripts.