I click on Morrowind, its green, I click on Skyrim, it changes from red, then to blue, then to green, then to blue, then to green when I keep switching back to it.

Anyone know what that means?

Steam switches the background colour and picture when you click on a different game. It's just the colour and picture the Steam assigned that time you clicked.

I'm not sure why it's only green for Morrowind, however. That's never happened to any of my games.