Are you able to try another TV or monitor?
Try the Vizio monitor on another computer.
Try another monitor on your computer or video source.
Determine if the "black square" problem follows the TV or stays with the computer/video source.
I suspect that the Vizio TV may have a loose "connection" inside. Some component or trace/wire that works most of the time and then due to vibration, heat, etc. disconnects and the image is momentarily lost.
Key is to isolate the problem to Vizio or source.