Windows 7 Windows Main Sreen Background

When I went to my computer this morning the color of the background on the active window ( I believe that is what it is called ) had been changed from an egg shell color to a seafoam (?) green color. Not only that but the active icon that were in the right hand side of the taskbar were gone. It was as if my computer had restarted and made changes. I got my icons back and I would like to get my eggshell screen color back but, when I go into "personalize advance setings" the eggshell color that I had is not there. I have attached a snippet of my screen so you can see the color of the screen I am talking about. Please disregard the pop up yahoo about the invalid username, I have been going round and round with yahoo mail about it. Thanks