My settings are exactly how they are when I first set up the hot spots many months ago. I move the cursor to the top left hand corner and the screen dims, but it doesn't show any of the windows open. E.G. at the moment I have Finder, Mail, iTunes and Safari open. The only way I can see that those are open is to click on the button for a few seconds and see the open windows, e.g. the open windows in Safari.
Do a reboot. Check one more time in software Update that the updates have been installed.