Samsung NV20 Manual page 15

3. Click Turn Off.
If the computer is not turned off properly due to a system error, press
<Ctrl>+<Alt>+<Delete>. When [Windows Task Manager] dialogs appears,
click Shut Down > Turn Off to turn off the computer. Your unsaved work may
be damaged.
If <Ctrl>+<Alt>+<Delete> keys do not operate either, press the power button
for more than 4 seconds to turn off the computer. Your unsaved work may be
damaged. When you turn on the computer next time, it will perform a disk
checking process.
Using Your Computer for the First Time 7