mobile

hi guys.
first of all im very happy with this phone, extremely fluid near the stock android experience.
but i would like to know if im not the only one with this "little problem".
sometimes while using the phone (it happened only 3 times), i remember while im downloading an app, like a game (2 gb for example), sometimes it stuck, the phone become unresponsive, connection (wifi) turns off, the speaker makes a strange sound (like buzz), and then after a bunch of seconds the phone return back, wifi reconnet, and the app (game or other) starts download.
anyone with this?

hope i helped to identify the problem.