Xpath error in Firebug (and Chrome)

I am working on a web app (mostly tables and forms, loaded from a database) that uses AJAX to load almost everything, and everything works in Internet Explorer but not in Firefox or Chrome. None of the pages load in Chrome or in Firefox.

One of the pages in question is a page with nothing but a table. I am creating the page in xml (using php) and then displaying it to the user in html using xslt.

Every time I load the page it stops loading after a second and the script tab in Firebug shows me the following function in xpath.js, highlighting the "else if"-row. When I 开发者_如何学Cpress F8 (Continue), FF bypasses the error and loads the page instantly.

function ExprContext(node, opt_position, opt_nodelist, opt_parent) {
  this.node = node;
  this.position = opt_position || 0;
  this.nodelist = opt_nodelist || [ node ];
  this.variables = {};
  this.parent = opt_parent || null;
  if (opt_parent) {
    this.root = opt_parent.root;
  } else if (this.node.nodeType == DOM_DOCUMENT_NODE) {
    // NOTE(mesch): DOM Spec stipulates that the ownerDocument of a
    // document is null. Our root, however is the document that we are
    // processing, so the initial context is created from its document
    // node, which case we must handle here explcitly.
    this.root = node;
  } else {
    this.root = node.ownerDocument;
  }
}

Any suggestions what could be causing this?