Problems installing Adaptec JAM 2.6

Several users are reporting problems getting the JAM 2.6 update to install. This has been a common refrain after virtually all recent Adaptec Toast and Jam updates (see this Forums thread for example). For example, Chris Gauch writes: " I tried reinstalling JAM, restarting with extensions disabled, the whole nine yards - no luck getting the Jam 2.6 updater to work. As soon as it begins to update Jam, the 2.6 updater chokes and reports 'the update could not be completed: Resources Modified (Code 0)'." Philippe Mingasson had the same problem. Reports on VersionTracker also confirm this. Other reader reports suggest that success or failure depends on what version of JAM you are trying to update. For example, Ollie Honauer could not update 2.5, but could update 2.1.