Background display problems

[Robbyx]

Has anyone seen the solution to the background pictures being turned into a good imitation of a knitted pullover? I am using the standard green background for the desktop and the pebble picture for the screen saver. The pebble picture losses all recognition and looks like a knitted cloth. I am getting similar green small squares in some entry boxes where I should see the emerald picture.

The Terraform-green.jpg is spanned. The Stones.jpg has no mode, having tried other modes and still getting problems.

I assume this is a common problem. What is the solution?

Robin