philipla from Support:
That definitely shouldn't be happening. Can you tell me more about the circumstances in which this mode gets enabled for you?
It's very interesting to see parental controls being implemented (referred to by Valve as 'Kid Mode'), and it's a step in the right direction for the Steam client.
It sounds like the scenario is this: You login, switch to Big Picture mode, go to your library, and everything is OK. At some undetermined point during browsing your library, the client flips into Kid Mode, and then you have to restart Steam, at which point the cycle eventually repeats?