Computer won't turn off screen or go to screen saver. Screen goes black for a second and comes back on. Also won't hibernate or sleep most the time

My computer won't turn off the monitor even though its set to do so at 5 min. It also won't turn on the screen saver (set at 4 min). The screen going black for a second and comes back.

What's worse is that hibernating used to work all the time, now it doesn't if the computers been on for about a day or so continuously. Sleep won't work either in the same situation.

Any idea why?

I'm using Windows 8.1

Submitted October 01, 2017 at 11:52AM by WeWantAmericaBack http://ift.tt/2xIP1DU