Hi, Rita,

How to use Apple Hardware Test on your Mac may help.

Originally Posted By: Apple
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Some Mac computers that shipped with OS X Lion v10.7 or later will start up from AHT over the Internet if your startup disk doesn't contain AHT, or if you hold down Option-D at startup. This requires an Internet connection over Ethernet or Wi-Fi.

If you're using OS X Lion v10.7 or earlier and you can't get AHT to start, see if you have an OS X installation disc named “Applications Install Disc 2.” Insert the disc in your internal optical drive or external Apple SuperDrive before following the steps above. Or, if you're using a MacBook Air (Late 2010), plug the MacBook Air Software Reinstall thumb drive into your USB port instead.

The new Great Equalizer is the SEND button.

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