<SCRIPT LANGUAGE="JavaScript">
...
            if(form.elements[i].name.indexOf(group_name) != - 1 ) 
...
                form.elements[i].checked = main_checkbox.checked; 
...

 <input id="main_checkbox_id" name="LogOff_users" type="checkbox" value="<%=rs_t(9)%>"> </td>


  <SCRIPT LANGUAGE="JavaScript">
function selectCheckboxesGroup(group_name , main_checkbox_id) 
    { 
        var form = document.forms['frm']; //Форма 
        var main_checkbox = document.getElementById(main_checkbox_id); //Чекбокс, который включает остальные чекбоксы 
        for(var i =  1 ; i < form.elements.length; i++) 
        { if(form.elements[i].name.indexOf(group_name) != - 1 ) 
            { 
                form.elements[i].checked = main_checkbox.checked; 
            }         }     } 
</SCRIPT>


 <input name="main_checkbox_id" type="checkbox" onclick="selectCheckboxesGroup('main_checkbox_id')" > 

<input name="main_checkbox_id" type="checkbox" onclick="selectCheckboxesGroup(this)"> 
<input name="main_checkbox_id0" type="checkbox" onclick="selectCheckboxesGroup(this)"> 
<input name="main_checkbox_id1" type="checkbox"> 

<script type="text/javascript">
function selectCheckboxesGroup(elem){
  var name = elem.name;
  var elems = document.getElementsByTagName("INPUT"); 

  for (var i =  0 ; i< elems.length; i++)
    if (elems[i]!= elem && elems[i].type=="checkbox" && elems[i].name && elems[i].name.match(RegExp("^"+name)))
      elems[i].checked=elem.checked
}
</script>