(key “1” stopped working BUT “!” still works when i press shift 1)

So just yesterday the key “1” stopped working BUT “!” still works when i press shift 1. When i started or restarted the computer, it works for about one minute then will stop.
I boost the computer to safe mode and it works just fine. And i try with a different keyboard, the same problem persist, so i doubt something’s wrong with the keyboard. Rather i suspect some process in the background is causing the problem.
I even tried restoring the system back to a few days ago and the same problem still persist. I am running out of ideas.
I use Window 8.1 by the way.