My Samsung Galaxy S 2 (4.0.3) turns audio back on without notice. I turn the silent/vibrate mode of the system on and it resets it, with no specific time. It just randomly turns the audio back on. Why is that? I've checked all my apps and apparently none of them is changing that option.
This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, see the FAQ.