that is pretty odd. I've had a Captiveowrks for a while now and never had it shut down.
Did you do anything to it that might make it shut down? Did you try and load new software into it?
So if you flip the switch off on the back of the unit and back on, it should come back up. The front menu should work.
If not, then you have a dead one and would have to send it back to the dealer you got it from.