A web app that loads and displays xml files using javascript and xsl stylesheets is breaking since upgrading to Firefox 7. These pages load successfully using Firefox 3 and 4, and all versions of IE. I can't figure out why, bit it breaks when returning to pages that have already been successfully loaded. Error console shows: "Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIDOMXMLDocument.load] ... data: no" but this is occurring for a file that had been successfully loaded previously. Additional info: I am getting the following warning for pages that do load successfully: Warning: Use of Document.load() is deprecated. To upgrade your code, use the DOM XMLHttpRequest object. I know I will need to deal with this issue sometime in the near future, but the structure of the data means that I need to load stylesheets from a directory above the directory containing the xml data being loaded, and the security features of XMLHttpRequest won't allow this. So a move to using XMLHttpRequest means restructuring the data, which is a major overhaul.