Christmas of 2015, I rebuilt my PC. Everything functions properly except two things. Sometimes, I hear the Windows popup notification sound, and my display goes out. Mind you, the PC is still on and active. In order to fix it, I have to restart my PC. I also noticed, sometimes after school (About once every month, or when doing a PC Scan) my PC locks up and blue screens. I don't know why is does it when I'm not on it, but when I log in I look at the error details and it says it blue screened. Help?