<form name='add' action='' method='post'><input type="hidden" name="id" value="1a490de70a18c8f888b4c633c6710ee3e8827cee498ccc8993979960638210" />
   <td width='10'><input name='chk_box' type='checkbox' value='1'></td>
   <td>Только локальный трафик</td>
   <td align='right'><input type='submit' value='OK'>
   <input name='act' type='hidden' value='1'>

   <input name='obj' type='hidden' value='CT141936/OB261193/CHECKBOXESCHBX_LOCAL'></td></form></tr>

FormItem: OleVariant;
..................
for i := 0 to WebBrowser.OleObject.Document.forms. Length - 1 do (1)
begin
 FormItem := WebBrowser.OleObject.Document.forms.Item(I);
 for j := 0 to FormItem.Length - 1 do                            (2)
  if (CompareText(FormItem.item(j).type, 'checkbox') = 0) and
         (CompareText(FormItem.item(j).Name, 'chk_box') = 0)then
         begin
           if FormItem.item(j).checked='checked' then
             FormItem.item(j).checked='';            
         end;
 begin
 end;
end;