When my computer boots up, the desktop display is alright until the windows desktop icons load. The display resolution then changes to 256 colours and I have to set the colour to true colour 32 bit. This happens each time the computer is restarted. How do I set the colour to remain at true colour 32 bit?
Have you tried to calibrate your display and seeing if that holds? http://windows.microsoft.com/en-US/windows7/Calibrate-your-display
In control panel you might have configuration settings specific to your video card. For example my NVIDIA card installed a "NVIDIA Control Panel" button in my control panel. You might have one for ATI or Intel GMA depending on the chip on your video card.
Try changing the color depth in the video card specific graphics settings instead of using the settings provided by windows.