Comment 1 for bug 1282753

I've managed to reproduce this even easier;

1) Open camera app
2) Click gallery button
3) swipe from the right to swap back
4) Immediately swipe back
5) Repeat

If you switch while the camera background is still black (ie you don't see the live previw, Step 4), when you switch back the camera will be locked and exhibit the behavior mentioned. It might take a time of two to get the timing right.