2014.5 installed clean about two months ago and worked fine, now has video problem. No other new software or known video driver updates installed. No similar problem in other software products.
In 2D model space, at the top and bottom of the drawing screen is some video debris. Moving the mouse pointer over the drawing makes the video debris flicker and change. With a drawing in the window, moving the cursor can make an even broader video image. A similar thing happens in paper space, affecting the same drawing space, not just the paper itself.
Dell Optiplex 7010 system. Mouse over other elements (menus, toolbars, etc) of the program causes no problems.
Any ideas?
UPDATE: It's worse!
When zoomed into a window from the original drawing, moving the mouse brings back the previous video view (the whole drawing) in place of the zoomed image. I can still select and delete items from the current zoom area, but working the former video flashing through is absolutely not productive.