My two monitors, ever hour or so go black with a small, white box in the centre of one, with the message "Can't find main file. Please reinstall screen saver". I have no idea what is creating this. I have no screensaver installed. Have you come across this message? Could it possibly be Directory Opus causing it?
I doubt Opus is involved here. What makes you think it might be?
Have you checked the Windows screen saver settings?