I've had a problem with my HP printer. I contacted their technical support and got help with it. They connected to my machine (a Windows 7 Ultimate, 64-bit) remotely and did some work on it. Naturally, as often happens in such situations, my desktop had a flat apparence. I've seen this happen before in other situations, but normally once the technical support person is done, the machine returns to it's normal appearance.
But not this time.
This time it still looks flat. The Aero style is totally gone. And I've noticed that when I pass my mouse over the items in my task bar, instead of seeing small images of the application running, all I see is a list of the various instances of that application running.
I don't like this appearance at all. I'd like to know why it didn't return to the Windows 7 theme and how to get the Windows 7 theme back the way it was.