I decided to open a thread about this because I think this might be useful for some people. I was having many issues with SP4 and was even thinking about returning it, blue screen of death, unresponsive touch screen after "sleep", etc. I read that many problems were caused by conflicts with the updates, so I decided to do a resfresh (keeping all my files) and doing all the updating again, taking my time with it and not rushing them. That was about 5 days ago and since then I haven't had any issue at all, and now the device is working as I expected it would when I bought it. I'm not sure if this will solve it for you, but it sure has worked for me, it's like another device now.