Artifact on screen after using ctrl+B

Hi guy’s, a scene made in blender 2.79 show this artifact on screen and even closing and reopening the scene it’s still showing.

If i open a new scene it’s OK nothing show up so is there a refresh screen or some wizardry to get rid of it?

You create a render area with Ctrl+B, and clear it with Ctrl+Alt+B.

Thank mate you nail it right on the head and saved me hours of searching!