OK, so for some reason I keep forgetting this. The Mac OSX Logitech control center screws up everything on the Mac. I had just installed it again last weekend and my hot corners stopped working, sub-menus required me to hold down the left click to stay active, and the only way the screen saver would work was based on inactivity timeout.
In hot corner (set for screen saver) or in screen saver test in System Preferences, the screen saver will start for a second or two then stop and return you to the main screen. I played around with it for a week or so then remembered that the Logitech Control Center had caused this exact same issue under Leopard and Snow Leopard. Well seems as though it’s still not fixed. I tried the latest 3.51 this time and it still screwed up the screen saver. If you are having a similar issue go to your Applications-utilities folder and uninstall LCC (Logitech Control Center).