Tabbing between application windows while using spaces The weirdest thing happened to me. I reinstalled OSX Lion on my macbook, and when all done I noticed how I could not switch between application windows on different spaces using cmd + tab. 

I'm positive I've been able to jump to different application windows that are on different space before. Now it will only switch to another application window if it's on the same space. If it's on another space, it will switch to the app but remain on the same space.

I've also noticed how I cannot jump to application windows on other spaces when I single click their icons in the dock.

Is there a stupid setting I've missed, or have I been living in a wonderful fantasy for many months while using Lion?
Have you got an existing screen sharing connection? It is one of the main reasons why switching between applications does not work. Failing that try restarting the dock by opening a Terminal window and enter the following command:

killall Dock