Document.all no firefox

var input = document.getElementsByTagName("input");

	for(var i=0; i<input.length; i++) {
		 if(input[i].type == "checkbox"){  
			 if (input[i].checked == true)
				 return true; 
		 }
	}

<script type="text/javascript">
		
		// A função abaixo pega a versão mais nova do xmlhttp do IE e verifica se é Firefox. Funciona nos dois.
		function createXMLHTTP() 
		{
		    try 
		    {
		        ajax = new ActiveXObject("Microsoft.XMLHTTP");
		    } 
		    catch(e) 
		    {
		       try 
		       {
		            ajax = new ActiveXObject("Msxml2.XMLHTTP");
		            alert(ajax);
		       }
		       catch(ex) 
		       {
		           try 
		           {
		                ajax = new XMLHttpRequest();
		           }
		           catch(exc) 
		           {
		                alert("Seu navegador não tem recursos para uso do Ajax.");
		                ajax = null;
		           }
		       }
		       return ajax;
		    }
		
		var arrSignatures = ["MSXML2.XMLHTTP.5.0", "MSXML2.XMLHTTP.4.0",
		"MSXML2.XMLHTTP.3.0", "MSXML2.XMLHTTP",
		"Microsoft.XMLHTTP"];
		for (var i=0; i < arrSignatures.length; i++) {
		    try {
		        var oRequest = new ActiveXObject(arrSignatures[i]);
		            return oRequest;
		        } catch (oError) {
		    }
		}
		
		throw new Error("MSXML is not installed on your system.");
		} 
		
		function RetornaDestinos(periodorota)
		{
		    var oHTTPRequest = createXMLHTTP(); 
		    oHTTPRequest.open("post", "retorna_destinos.asp", true);
		    oHTTPRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
		    oHTTPRequest.onreadystatechange=function() {
		       if (oHTTPRequest.readyState==4){
		        document.all.exibedestino.innerHTML = oHTTPRequest.responseText;
		       }
		}
		
		oHTTPRequest.send("periodorota=" + periodorota);
		
		}	


		function RetornaRotas(destinorota)
		{
		    var oHTTPRequest = createXMLHTTP(); 
		    oHTTPRequest.open("post", "retorna_rotas.asp", true);
		    oHTTPRequest.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
		    oHTTPRequest.onreadystatechange=function() {
		       if (oHTTPRequest.readyState==4){
		        document.all.exiberotas.innerHTML = oHTTPRequest.responseText;
		       }
		}
		
		oHTTPRequest.send("destinorota=" + destinorota);
		
		}	


</script>

function abremenu(x){
	if (IE) {
	document.all.divinfos[x-1].style.visibility="hidden";
	document.all.divinfos[x-1].style.display='';
	document.all.divinfos[x-1].style.filter="blendTrans(duration=.5)";
	document.all.divinfos[x-1].filters.blendTrans.Apply();
	document.all.divinfos[x-1].style.visibility="visible";
	document.all.divinfos[x-1].filters.blendTrans.Play();
	}
}

function fechamenu(x){
	if (IE) {
	document.all.divinfosdivinfos[x-1].style.visibility="hidden";
	document.all.divinfosdivinfos[x-1].style.display='none';
	}
}