Strange Screens Update
The mystery was solved
Just before work escalated to the point where I had to make time in my schedule just to breathe I ran into a strange problem with two of my screens. I wrote about it and posted a picture at Strange Happenings …
A day or two after I posted that my wife identified that strange image - it comes from Yahoo’s Konfabulator and apparently there was a conflict involving that programme and something else on that particular computer.
Once I ditched Konfabulator the image disappeared and never returned. Other problems did continue to appear and in the end we migrated the system into a smaller box - like this one and took the opportunity to format the hard drive and reload the operating system.