Apple Mac mini (Intel-based; Mid 2007) - Manual (Page 35)

Chapter 3 Problem, Meet Solution 35
If your date and time settings get lost repeatedly
 You may need to have the internal backup battery replaced. See “Learning More,
Service, and Support” on page 41 for information about contacting Apple for service.
Using Apple Hardware Test
Use Apple Hardware Test to determine if there is a problem with your Mac mini.
To use Apple Hardware Test:
1 Disconnect all external devices from your Mac mini, except the keyboard and mouse.
If you have an Ethernet cable connected, disconnect it.
2 Insert the Mac OS X Install Disc 1 that came with your Mac mini.
3 Restart your Mac mini and hold down the D key as it starts up.
4 When the Apple Hardware Test language chooser screen appears, select the language
appropriate for your location.
5 Press the Return key or click the right arrow button.
6 When the Apple Hardware Test main screen appears (after about 45 seconds), follow
the onscreen instructions.
7 If Apple Hardware Test detects a problem, it displays an error code. Make a note of the
error code before pursuing support options. If Apple Hardware Test doesn’t detect a
hardware failure, the problem may be software-related.
For more information about Apple Hardware Test, see the Apple Hardware Test Read
Me file on the Mac OS X Install Disc 1.