I just upgraded my Mac Mini 2.4GHz, 8/320. Unfortunately, massive issues have occurred. My other Mini didn't experience any of these issues. First off, under the Apple tab, the ForceQuit keeps blinking between the words "Force Quit..." and something Chrome (if that's the program that is open). I can select it and ForceQuit either one, but neither fixes the flashing issue. Logging out every 3rd time or so might solve it, but it returns eventually. Secondly, regarding the 3 circles which expand, close or hide a window in the upper left corner of every window, I am no longer able to use. Close, hide or expand isn't accessible using those buttons. Clicking them is useless. I have to Control+click to get the contextual menu in order to close the tab or window. Thirdly, when a dialog box opens, I have to use the Tab and Spacebar to enter an option. The Enter/Return key no longer selects "Ok" as an option. I have to tab around to highlight it, then hit the spacebar. These issues occur system-wide and aren't program specific. We have also lost the ability to Command+Tab to select the open program. All it does is switch from the open program back to Finder. The program icon which used to come onscreen as this keyboard command is being used no longer comes up. I'm wondering if upgrading to 10.10.3 will alleviate these issues, although I haven't read about any them yet. If all else fails, I'm going back to Mavericks using Time Machine.