When the Windows 7 taskbar is set to auto-hide and an MFC-wizard created SDI app is maximized (via a mouse click) , the Windows taskbar will no longer unhide when the mouse is moved to the bottom of the screen. (The little, telltale row of pixels indicating that the taskbar is hidden are also not visible.) If you restore the app's window, the taskbar still won't unhide. However, if you change the focus to another window, the telltale row of taskbar pixels reappear and the taskbar will unhide correctly.
This was problem was identified running Windows 7 Professional, version 6.1.7600 Build 7600. The app was built using Visual Studio 2010, version 10.0.30319.1 RTMRel. This problem was duplicated on a second computer.
(This issue was initially reported on the Visual C++ Developer Center Forum. You can read that thread at: http://social.msdn.microsoft.com/Forums/en-US/vcgeneral/thread/3cafd80f-02bf-4dde-a5dd-89e93f64f3a4).