An update to the plugin is available, digitally signed, at the updateURL specified in install.rdf. Plugin works if installed manually. Version numbers and mime-types seem to be correct. Since the release of Firefox 5 updates are not being detected automatically. Clicking "Find Updates" manually produces no output, not even an error report. This is even the case when update.rdf is removed and so Find Updates should, presumably report a problem locating the file. I'm guessing therefore there is something wrong with the updateURL in install.rdf but I'm stumped as to what. All users report same problem.