From the investigations so far, the current issue seems likely to be specific to a certain piece of software that needs to be updated, but for which we may have broken update information from the publisher.  We are trawling through the list looking for potential culprits, but if anyone experiencing this issue current can go to Tools > Software Updater and provide the list of "Programs to Update" and the list of "Up-to-date Programs" this may help us narrow things down faster.