This question has just about killed my project. (that's why its crippling ) I've debugged it and tried many different bug fixes and observed it and tried to figure out how the heck to fix it so many times that I think my mind is numb to it.

The sad part is, it's not even an error, just a bug that I can't fix.

Okay, now that I've vented a little, I'll actually tell you my problem. I'm in the process of designing a forum, although I'm stuck on the login/logout/register process. An AJAX script takes the registration info from a form, creates an XML document with all the old user info plus the new user, stores that code as a string in a var which gets passed to PHP, and PHP overwrites the old XML file.

So it goes:
- User clicks the register button
- Javascript constructs the code and stores it as a string in the var
- AJAX passes it to PHP
- PHP rewrites the XML
- The page reloads

Very beta so far, no form validation or anything. The problem: The script randomly does not work AT ALL. No users get added or anything. It just doesn't work. Sometimes the xml file is updated. Sometimes its not.

/////////////////////// AJAX - the bridge between server and client
var AJAXfailmsg = "Browser Error!\nYour browser is too old and does not support the necessary technologies 

for this forum. Try upgrading your browser to one with AJAX support.\n"; // Message for AJAX failure
var forum=loadXMLDoc('forum.xml'); // XML document variable
var numUsers=parseFloat(forum.getElementsByTagName("users")[0].getAttribute("num")); //parseFloat the 

number of users for use in calculations and loop conditions

function loadXMLDoc(dname) // Load XML doc // Dname is the path to the database
var xmlDoc; // initialize a var to be used later
if (window.ActiveXObject) // code for IE
  xmlDoc=new ActiveXObject("Microsoft.XMLDOM");
else if (document.implementation && document.implementation.createDocument) // code for Mozilla, Firefox, 

Opera, etc.
else // no browser AJAX support
  alert(AJAXfailmsg); //Alert with fail message
xmlDoc.load(dname); // load the file
return(xmlDoc); // returns the XML doc when this function is called

function ajaxFunction(messageDat){ // the Ajax Request Function
	var ajaxRequest;  // initialize a var for later
		// Opera 8.0+, Firefox, Safari
		ajaxRequest = new XMLHttpRequest();
	} catch (e){
		// Internet Explorer Browsers
			ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
				ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e){
				// No AJAX message:
				return false;
	// Create a function that will receive data sent from the server
	ajaxRequest.onreadystatechange = function(){
		if(ajaxRequest.readyState == 4){ //If the server is done...
			alert("Success!"); // Alert
	// Send it!"GET", "forumWrite.php?newXML="+messageDat+"", true); 

///////////////////////////// Javascript newXML construction - create the XML and use AJAX to pass it to PHP
// The following 3 functions return a string of XML

function users(typeCall) //Returns the users
var users2 = parseFloat(forum.getElementsByTagName("users")[0].getAttribute("num"))+1;
if (typeCall=="old") // If you want the complete old database of users...
var usersStr='<users num="'+forum.getElementsByTagName("users")[0].getAttribute("num")+'">';
for (i=0; i<numUsers; i++) // Write user data for each user


else if (typeCall=="add") // if you want to write the old database and add a new user...
var usersStr='<users num="'+users2+'">';
for (i=0; i<parseFloat(forum.getElementsByTagName("users")[0].getAttribute("num")); i++) // Write user data 

for each user


// no </users> tag because you are adding a user: all <user> tags have to be inside the <users> tag...
return usersStr; // return the users xml data

function config()//Returns the config settings
var configsStr = '<config>empty</config>';
return configsStr // return the config xml data

function database()//Returns the actual categories, threads, boards, posts, etc.
var databaseStr = '<database>empty</database>';
return databaseStr // return the database XML data

function registration()
var newPHPXML; // This variable will contain new XML data to be written over the old
newPHPXML = '<?xml version="1.0" encoding="UTF-8"?><forum>'; // Beggining data
newPHPXML+=users("add"); // populate with former users,
newPHPXML+='<user><username>'+document.register.username.value+'</username>'; // add new username
newPHPXML+='<password>'+document.register.password.value+'</password>'; // add new password
newPHPXML+='</user></users>' // a few end tags
newPHPXML+=config(); // configs
newPHPXML+=database(); // and the categories, boards, threads, posts, etc.
newPHPXML+='</forum>' // Ending data
var escapedPHPXML = escape(newPHPXML); // newPHPXML escaped for transfer through the _GET superglobal var.

ajaxFunction(escapedPHPXML); // Use AJAX to pass the escaped newPHPXML
document.location=document.location; // goes to another page/reloads
<script src="func.js"></script> <!-- the above JS file^^^ -->
<form name="register">
Username: <input type="text" value="admin" name="username"><br>
Password: <input type="password" value="admin" name="password"><br>
Password Verification: <input type="password" value="admin" name="passwordVerification"><br>
<input type="button" onClick="registration()" value="Register">
PHP: (there's nothing wrong with it, I'm pretty sure. But for reference purposes forumWrite.php:
PHP Code:
/* The very small PHP frontend function for exBB.*/

if (get_magic_quotes_gpc()) { // If magic quotes are enabled...
$newXML stripslashes($_GET['newXML']); // Strip the slashes and get the var
// Slashes before quotes in the XML file will cause errors
} else { // If there not..
$newXML $_GET['newXML']; //Get the variable

$myFile "forum.xml"// path to the forum database
$fh fopen($myFile'w') or die("Internal forum error!"); // open the database
// Completely overwrites the old data instead of only appending to the end
$stringData $newXML// the data to be written
fwrite($fh$stringData); // actually write it
fclose($fh); // close the file
I am so desperate on this question. It has brought my forum to a screeching halt. I have figured out this:

- It isn't that the AJAX reads the old XML before it is updated

Anyone please help!