Can I validate that I am having the same issue as others?
My "random tap issue" is the screen just starts to go crazy, lots of taps, scrolling, and capacity button clicks(can feel my phone vibrate like i am hitting one of the three buttons). Cortana will come up, start screen will display, and the multitask display will come on. Just seems like a thousand fingers are touching my screen.
My biggest issue with this is it hangs up my calls, or hits the hold button if I take it away from my face at all. Really is annoying. As far as people thinking this is a hardware issue, I didn't have this issue before 8.1, maybe others did. This phone was perfect before going to 8.1 DP, and now 8.1 on AT&T.
Sometimes my phone locks up when trying to unlock and I assume it's the same issue. Too many things "touching" the screen making the phone appear to be locked up. To me, it's all the same issue.