Hold the Power button for about 10 seconds then Restart the computer and immediately hold the Shift key until you see the Apple Logo. This is called Safe Boot and it will attempt repairs. If you get to the login screen put in your user/pass then when it boots up, restart the normal way. Let me know what happens after.
Ok I am here if the problem persists, let me know... If you are satisfied, please kindly provide an OK or Above Rating - so I get paid. Keep in mind you can always come back to this page at any time regarding this question. If we solved your problem, giving me high marks on the survey and / or bonuses are also GREATLY appreciated. Thanks!!