var send_once = false

function lockform(fm) 
{
	var agt=navigator.userAgent.toLowerCase();
	var is_major=parseInt(navigator.appVersion);
	var is_minor=parseFloat(navigator.appVersion);
	var is_nav=((agt.indexOf('mozilla')!=-1)&&(agt.indexOf('spoofer')==-1)
              && (agt.indexOf('compatible') == -1) && (agt.indexOf('opera')==-1)
              && (agt.indexOf('webtv')==-1) && (agt.indexOf('hotjava')==-1));
	var is_ie =((agt.indexOf('msie') != -1)&&(agt.indexOf('opera') == -1));
	var is_nav6up=(is_nav && (is_major >= 5));
	var is_ie4up=(is_ie && (is_major >= 4));

	if ((is_nav6up)||(is_ie4up))
	{
		for (var i=0; i<fm.elements.length; i++) 
		{
			if (
				(fm.elements[i].type == 'submit')||
				(fm.elements[i].type == 'reset'))
			{
				fm.elements[i].disabled = true;
	    	}
		}

		return true;
	}
	else
	{
		if (send_once)
		{
			alert('You already pushed the button - please wait!');
			return false;
		}

		send_once = true;
		return true;
	}
}