have you read AUS Update XML File Malformed 200

OK, I checked for everything suggested in "AUS Update XML File Malformed 200" and none of the suggestions seemed applicable: I have no extension named Noscript, I can access secure sites, the url in "about:config" cannot be reset, I have no cookie named "aus2". --But the MERE ACT of trying these suggestions made my "XML File Malformed 200" message go away, at least temporarily -- I can now click Help/CheckForUpdates and the "Malformed" message does not appear, instead a message appears saying (words to the effect of) I have the most recent version, which is true by comparison of Help/About and the version number at the Firefox Updates site.