change the code for the text box:
<input type="checkbox" name="AsstAgreeToTerms" id="AsstAgreeToTerms" value="YES" class="formCheckboxField_Standard" <?php if (!(strcmp((isset($_GET["invalid"])?ValidatedField("assistantsconfirmupdate","AsstAgreeToTerms"):"".$row_WADApcms2_users["AsstAgreeToTerms"].""),"1"))) {echo "checked=\"checked\"";} ?> tabindex="16">
to:
<input type="checkbox" name="AsstAgreeToTerms" id="AsstAgreeToTerms" value="YES" class="formCheckboxField_Standard" <?php if (!(strcmp((isset($_GET["invalid"])?ValidatedField("assistantsconfirmupdate","AsstAgreeToTerms"):"".$row_WADApcms2_users["AsstAgreeToTerms"].""),"YES"))) {echo "checked=\"checked\"";} ?> tabindex="16">