Monitor doesn't turn off

Ok, I have it set up just like I did with Win7. Screen saver set for 10 minutes, monitor power off set for 15 minutes. The problem is, the monitor doesn't turn off! To be more accurate, it DOES turn off at the 15 minute mark, for about 1 minute. Then it turns back on and the lock screen shows. Then after 1 minute, the display fades out to black, but the monitor itself is still on. I've...