function clickIE() 
{
  if (document.all) 
  {
  return false;
  }
} 


function clickNS(e) 
{
   if (document.layers||(document.getElementById&&!document.all)) 
   { 
      if (e.which==2||e.which==3)  
      {
         return false;
      }
   }
} 

if (document.layers) 
{
   document.captureEvents(Event.MOUSEDOWN);
   document.onmousedown=clickNS;
} 
else
{
   document.onmouseup=clickNS;
   document.oncontextmenu=clickIE;
} 
document.oncontextmenu=new Function("return false")