Computer Locks when screensaver or monitor cuts off

Only when vDownloader is downloading videos; does not matter what site it's pulling from.

When vDownloader is actively downloading video and the monitor cuts off due to inactivity I find that the computer locks up.  I must physically power off and back on to regain video.  (The keyboard lights do not even turn as they normally would if the PC were working and the monitors off.)

I have
Windows 10 v1709
vDownloader 4.5.2902.0
My output format is mp4 with video codec MPEG-4 and audio AAC at 44100