Video link resets whenever I move the mouse

I haven't played Sins in a few weeks, so a few things could have changed.

First, the Sins game could have been updated.

Second, the Nvidia driver was recently updated.

Third, there was a recent Windows 10 1809 update.

When I tried to play Sins tonight it would load just fine. And I could use the keyboard to switch controls and Enter to apply them. But whenever I moved the mouse the monitor went blank and the monitor lights indicated no signal. Then it would restart the video link and the monitor would come back in a few seconds.

It was not a driver crash because Youtube videos on the second monitor continued to play.

Other games worked fine.

Sins seemed to work in windowed mode.

The monitor is a 3840x2160 G-Sync on an Nvidia 1080 Ti.

And ideas or fixes for this?