OK - I'm not currently on-site at the venue, and the issue isn't something I've yet experienced in person, but the LD who's running a show this week has twice now had a problem when powering down the Gio console.
Hopefully I can describe the issue - I'll correct any shortfalls if I find any 
I'm not sure what s/w version we are at with the console, but I think we are at ver 3.3.4.21 - I can check tomorrow if I can drop by the theatre.
After the usual power down sequence from the CIA the system hangs with the display showing as below. This screen basically sits there and he cannot get any further and no amount of clicking on 'YES' has any effect.
He has managed to shut the console down from here by literally switching off at the rear on/off switch, and subsequent restarts/shutdowns have worked OK. But as this has happened twice in two days gives me cause for concern.
Any thoughts what this might be?