Mine started doing this earlier this week started as knock on not working, then today I couldn't slide the brightness bar in the notification menu. I think for me this has to be software related, because when I enable quick remote the area in side the quick remote box in the notification screen is plenty sensitive and registers all touches. When browsing the area registers all touches as well. I bought the phone used about 5 months ago. Definitely disappointing but as it is I can work around it.