function mdown( e )
{
    if( ( navigator.appName == "Microsoft Internet Explorer" && event.button & 2 ) || ( navigator.appName == "Netscape" && e.which == 3 ) )
    {
        alert( "右クリックは使用禁止です" );
        return( false );
    }
}

if( document.all )
{
    document.onmousedown = mdown;
}
if( document.layers )
{
    window.onmousedown = mdown;
    window.captureEvents( Event.MOUSEDOWN );
}