Bug within Mac OS Sierra?

Since updating my Mac to OS Sierra I’ve been having problems. Firstly my keyboard is not functioning as it should be. It will all of a sudden start typing symbols, caps lock won’t work neither will space and sometimes other keys won’t work. Caps lock light turns on when using a USB keyboard. But sometimes symbols will stil type using that. iTunes won’t play music sometimes too. It will just have a message about clearing the next list of songs. When you click okay it still won’t play. I have erased the hard drive, and re installed Mac OS Sierra. I have checked all settings for keyboard. HELP