As Leigh alluded to, my second client called today to report the problem recurred there, once again at 5PM!!!
I was able to log in and see the error message that all Lanpaks were used, followed by the Access Violation message. Unfortunately, the user was restricted from clicking on Help (can you believe that!) and by the time I logged out and gave her rights, the situation cleared.
The user was editing Items from within OE when she was summarily kicked out with the Lanpak error message that all Lanpaks were in use.
The 5PM timing and where the user got the error stengthen my hypothesis that this problem occurs when for a moment two simultaneous events occur - editing a customer or item from a non-native module, and someone else exiting out of Adagio. I wonder if the exiting from Adagio temporarily locks the license counter file, which coincides with the request for another license when editing from a non-native module.
Steve