Dock and task bar disappearing from screen.

I've had the dock present and on screen since I switched to IMAC but now after an Apple update for security the dock disappears when I open an app and so does the upper task bar. After fishing around using the mouse at the bottom or top of the screen they pop up. When I close the app the dock is no longer visible. My setting is set at bottom location. Any recommendation(s) would be appreciated.

Have you checked your "Dock" settings in "System Preferences"? There's a setting there for "Automatically hide & show the Dock". With this box checked...unless your mouse pointer is hovering over the dock...the dock will automaticaly "hide".

- Nick