So our institute upgraded to 5.0.15 over the weekend from 5.0.10 and first thing Monday morning I upgraded a few people (myself included) to the ZCO 5.0.15. Frank had let me know that the calendar conversion should be markedly better than 5.0.10, and it seems to be so, because my small group of people in a department here (who all share their calendars with each other and view them all in Outlook) all had synchronizations marked as Completed, rather than Failed, when syncing up the shared folders. It was magical. I can't say with 100% certainty that it continued to do so properly after I walked away from the first few syncs, but I haven't heard anything, and am optimistic.
I still got Local Failure Notices for each person, and a lot of them have details like:
**INCOMPLETE ATTENDEE with display name [no display name] and no email
address will be removed from the appointment**
but I don't know how to interpret that. When I look at the MIME for the specific ID referenced, I see that it's an email msg, not an appt, so I am not sure what to make of it. I would like to understand how to interpret the many items listed in the Local Failure Notices, but I don't seem to actually have a problem.
As for Outlook.exe closing or not, well, to be honest, I am no longer quite sure whether the Outlook-never-stops-syncing problem was the only contributing factor. It certainly didn't help, but even with clean syncs, every now and then the user still has to kill outlook.exe and winword.exe after exiting (and waiting a reasonable amount of time). I was already familiar with the iTunes add-in and Skype as two common culprits for this in general, but that doesn't seem to be the problem. We eliminated malware recently on the computer, so maybe there's a vestige of a silly smiley toolbar that's still hanging on to Outlook in this one case. (By the way, the 5.0.15 ZCO installer nicely tries to avert the iTunes add-in problem by offering to disable it for you at the outset.) :-)
Many thanks to Frank for helping out along the way.