check box if select one un-select all other

Ok, so i have a list of check boxes 1, 2, 3, 4 and 5. I would like the function to select 2, 3, 4 and 5 but if 1 is selected then un-select 2, 3, 4 and 5, once 2 to 5 are un-selected display a message in a div.

So far I can select 1 and one of the others... and the message comes on selection of 1

problem 1 I cant un-select 2 to 5 once 1 is selected

problem 2 The message is displayed on page load even if the box is un-selected.

HTML

 <input type="checkbox" class="" value="checkbox" name="CheckboxGroup1" id="boxchecked"  />
one <br/>

<input type="checkbox" class="check" />
two <br/>

<input type="checkbox" class="check" />
three <br/>

<input type="checkbox" class="check" />
four <br/>

<input type="checkbox" class="check" />
five

<div id="hidden">Two to five can not be selected whilst you have one selected</div>

JavaScript

$('input.check').on('change', function() {
    $('input.check').not(this).prop('checked', false);  
});

$(document).ready(function(){
  $("#boxchecked").click(function ()
  {
      if ($("#boxchecked").is(':checked'))
      {
          $("#hidden").show();
      }
      else
      {
          $("#hidden").hide();
      }              
  });
});

$('input[name=CheckboxGroup1]').attr('checked', false);