[Javascript] AJAX "waiting"?!

[list at tridemail.de (Michael Borchers)]

the following functions work well. they call a php script via AJAX which 
returns  text.
the text  is parsed into an confirm.
when i try to directely acces the php file while the confirm remains opened,
it seems to hang up loading. is this because the first httpRequest hasn't 
closed yet
and only closes when the confirm is done?!

function getTasksReminders()
{
 httpRequest.open('get', 'ajax.php?ajax_filename=check_tasks.php', true);
 httpRequest.onreadystatechange = function() { remindTasks() };
 httpRequest.send(null);
}

function remindTasks()
{
 if(httpRequest.readyState == 4)
 {
  if(httpRequest.responseText != '')
  {
   confirmTasks = confirm(httpRequest.responseText);
  }

  if(confirmTasks == true)
  {
   document.location.href = 'tasks.php?select=1&search[users_id]=1>';
  }
 }
}