I'm trying to implement my own "Save and Close" button on an
appointment form. In my button-click handler, I am calling
_thisAppointment.Save(). The item does get saved, but I also get an
exception

"The operation cannot be performed because the message has been
changed."

The error code is -832306935. Does anyone know what will cause this
exception? I'm able to save the item by pressing ctrl-S with no
errors.

Thanks,
John