Every time I try to use this update, it downloads from the software update application, says it's been successfully updated then comes up with the screen saying to shut down. After the computer has shut down, I restart. The white screen with the apple logo comes up, the computer shuts down and restarts again. This happens every time. Then once the computer has loaded the second time (only ever restarts twice) the software update pops up and says the update was unsuccessful and asks me to shut down again. What's the delio?