I assume the same , that the machine is in the proccess of logging off or refreshing the session, or perhaps a stale token etc..
is there away to link specific issues to specif messages, so if the problem is that the user just logged off and is logging back in, and the machine is still made ready, that a message to that affect can be customised
something along these lines may be useful - "your machine is made ready - please wait...."( i know, not the most creative message)
also, where are these events stored/logged, i would like to be ble to evidence the reason this is showing so i have a more definitive answer to my clients/users.