Apple iMac (21.5-inch, Late 2011) - Manual (Page 43)

43 Chapter 4 Problem, Meet Solution
 Press the power button (®) and immediately hold down the Command (x),
Option, P, and R keys until you hear the startup sound a second time. This resets the
parameter RAM (PRAM).
 If you recently installed memory, and your iMac sounds tones every five seconds,
make sure that the memory is correctly installed and that it is compatible with your
iMac. Check whether removing the memory you installed allows your iMac to start
up (see page 38).
 Unplug the power cord and wait at least 30 seconds. Plug the power cord in again
and press the power button (®) to start up your iMac.
 If you still can’t start up your iMac, see “Learning More, Service, and Support” on
page 54 for information about contacting Apple for service.
If you have trouble inserting a disc
 Using a continuous motion, push the disc into the drive until your fingers touch the
edge of your iMac.
 Use only a standard-size disc.
If you have trouble ejecting a disc
 Quit any applications that may be using the disc, and then press the Media
Eject key (C) on your keyboard.
 Open a Finder window and click the eject icon next to the disc icon in the
sidebar, or drag the disc icon from the desktop to the Trash.