I don't have a T2, I still have a VA7. In rare occasions I've had a hang up as well - the sound in that case didn't stop: it sounded like it crashed. Very annoying 'digital' tones were then coming out.

The only solution was restarting the board, I've also tried reloading the firmware in it at that time. After that it happened only once. Next week I will have to play for about 7 hours, and I think it will go just fine...

I think you have done the right thing chony: just restart the thing and it should go well again.

It's a computer, that means per definition that it can crash...