UPDATE: seems it does not have to do with Steam overlay, but Big Picture itself. My OS was set to automatically turn the screen off after 3 minutes of inactivity. If that happened, Big Picture would show the issue, regardless of the overlay being active or not.
Anyway, as a temporary fix, I just disabled that feature in my OS, but the issue remains: whenever the system turns off the screen, Big Picture is prone to crash.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Using (the new) Big Picture mode, whenever I bring up Steam overlay, if I left it idle for some time, it will become "locked". Only the gray/blue background will be shown, along with the bottom black bar with the options "menu" and "abort game", both which don't work.
Gamepad commands are futile to get out of this, although, sometimes, you can issue an alt-tab shortcut to get back to the game. Mouse inputs work. You need to bring the menu, select "home", then the game you're playing, then "resume". However, results vary, you can either:
A. Get to the game and everything is fine; or
B. Get to the game, but you seem to be controlling Steam overlay from behind; or
C. The game soon crashes.
This happens with many games tested.
Steps for reproducing this issue: