HP Compaq Presario CQ42-210AU Notebook PC - Manual (Page 81)

If the computer is unresponsive and you are unable to use the preceding shut down procedures, try the
following emergency procedures in the sequence provided:
● Press ctrl+alt+delete , and then click the Power button.
● Press and hold the power button for at least 5 seconds.
● Disconnect the computer from external power, and then remove the battery.
Shutting down the computer 71