Buggy screen or proximity sensor

[hn2008]

Hello please tell me why I have all except the original firmware (3.3.7) often do not unlock the screen after the call? It's not the hardware and software chat 100%. Here's a link to the video (not mine) http://youtu.be/9V0UDKeGVqY

[zakirox123]

no worry buddy its an ICS bug there is nothing problem with your device, if you want you can just try it repairing with SUS, if the problem araise again then wait till JB release no worry life is just short enjoy as much as possible its just a device buddy.

[Rickard]

This has to do with how you're holding the phone. If you tilt the phone too much (like in the video) it assumes you want to use the display and it disables the proximity sensor. When you don't touch the display it will turn off display to save power after the configured display sleep time.
Try the sensor holding the phone upright like how you would hold it during a call.