AJAX+M$ (spells desaster)

Hi all

I have made a simple RPC to pull dynamically help texts from an xml file by using php and AJAX.

Everything works in both FireFox and M$ Explorer, with one exception:

If an element is already selected and the refresh button is pressed then m$ throws an error because apparently it fires the onfocus event before the onload event and my onload event is where the http object gets initialized.

Here is my script

                  // AJAX Functions
                  var helptitle='helptitle'; //name of the helptitle div
                  var helpbody='helpbody'; //name of the helpbody bidv
                  var cache=new Array();
                  var http;

                  function inithelp()
                  {
                        http=createRequestObject();
                        requesthelp('init');
                  }

                  function createRequestObject()
                  {
                        var reqobj;
                        var browser=navigator.appName;

                        if(browser.indexOf('Microsoft')!=-1)
                        {
                              reqobj=new ActiveXObject('Microsoft.XMLHTTP');
                        }
                        else
                              reqobj=new XMLHttpRequest();
                        return reqobj;
                  }

                  function requesthelp(field)
                  {
                        if(field=='init')
                        {field=new Object();
                         field.id='init';
                        }
                        if(in_cache(field.id))
                        {
                              get_cache(field.id);
                        }
                        else
                        {
                              http.open('get','contact.php?field='+field.id+'&action=help');
                              http.onreadystatechange=fillhelp;
                              http.send(null);
                        }
                  }

                  function in_cache(what)
                  {
                        if(cache.length>0)
                        {
                              try
                              {
                                    for(var counter=0; counter<cache.length; counter++)
                                          if(cache[what])
                                                return true;
                              }
                              catch(bug)
                              {
                                    ;
                              }
                        }

                        return false;
                  }

                  function get_cache(what)
                  {
                        try
                        {
                              fillhelp(cache[what]);
                        }
                        catch(bug)
                        {
                              ;
                        }
                  }

                  function fillhelp(fromcache)
                  {
                        var response,update;
                        var cheat=true;

                        if(fromcache==undefined)
                              cheat=false;

                        if( (http.readyState==4) || (cheat))
                        {
                              response=(cheat?fromcache:http.responseText);
                              update=new Array();

                              if(response.indexOf('|')!=-1)
                              {
                                    update=response.split('|');
                                    document.getElementById(helptitle).innerHTML=update[0];
                                    document.getElementById(helpbody).innerHTML=update[1];
                              }
                              if(!cheat)
                               cache[update[0]]=update[1];
                        }
                  }