I've am having an odd problem with my monitor, which is a 10 year old Sony CRT. I am using windows xp (5 year old dell) with the standard windows xp theme (blue for window pane colors) and lately the colors on the screen will suddenly change. After the change, the window pane colors are become purple, the start button becomes red (was green), and everything seems a bit dim.

Sometimes I can reset the display by choosing a new theme, but not always. (while typing this thread the display reset itself on its own)

Is this more likely a hardware issue such as monitor or graphics card, or is there an OS problem?

Thanks for any suggestions.