You Must Restart Your MacBook Now
Got this error message from my machine 2 days ago, this is the first time I saw Apple Macbook error message, the reason why the message popup was because I have accidentally removed my mobile phone USB charger without doing proper removal/hardware eject.
Only Choice, Restart It!
When you see this screen appear, the only thing you can do, hold the Power Button, turn your Macbook off and turn it on again. It’s similar to Microsoft “blue screen”, but as always, Apple give you better User Interface experience