This could be due to a Windows update, not sure. What you are seeing is the video card in a particular color mode, and the desktop and some other application are using different color modes. If you are using a virtual desktop application, or any application at all (desktops are applications), and the video mode itself does not switch, then you will see the effects of the difference between actual video/color mode and what the application intended.
The question then becomes one of why the two are running at different settings. What exact applications are running? Is this the default desktop, or have you added software? What applications does this occur with? Does this not occur with other applications? So on. Whatever the applications are, it seems you need to be able to find the color depth/format for each application. The system defaults would normally be the same as the desktop itself unless another application has changed the mode (e.g., a game).