Without delving into firmware and other issues I have found the a full reboot (where you see the moon on the boot screen) after streaming Netflix or when the box gets slow or unresponsive really helps. However, navigating anywhere will usually lock up the box at some point so,
- Power down the box.
- Start the box up again.
- Watch for the Moon picture on the boot screen and if you don’t see it, turn the box off before it fully reboots.
- Turn the power on and you will see the screen with the moon and get a full reboot.
Your box should run like you just pulled the power plug to reboot it - without pulling the plug.