Hello, Every now and then the End Call button will refuse to work (it doesn't even get highlighted when pressed), usually for up to 5 seconds. As you can imagine this can make ending a conversation considerably awkward. Any ideas as to what would be causing this? I first thought it could be the proximity sensor/screen lock, but the screen would have to turn off when this is in effect, which it doesn't. I can see the screen perfectly, I just can't interact with the End Call button. Is there any other way to end calls? Thanks!