Apple iMac (21.5 and 27-inch, Late 2009) - Manual (Page 50)

50 Chapter 4 Problem, Meet Solution
6 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.
If this procedure doesn’t work, you can insert the Applications Install DVD that came
with your iMac to use Apple Hardware Test. For more information, see the Apple
Hardware Test Read Me file on the Applications Install DVD.
Problems with Your Internet Connection
Your iMac has the Network Setup Assistant application to help walk you through
setting up an Internet connection. Open System Preferences and click Network.
Click the “Assist me” button to open Network Setup Assistant.
If you have trouble with your Internet connection, you can try the steps in this section
for your type of connection or you can use Network Diagnostics.
To use Network Diagnostics:
1 Choose Apple () > System Preferences.
2 Click Network and then click “Assist me.”
3 Click Diagnostics to open Network Diagnostics.
4 Follow the onscreen instructions.
If Network Diagnostics can’t resolve the problem, there may be a problem with the
Internet service provider (ISP) you are trying to connect to, with an external device you
are using to connect to your ISP, or with the server you are trying to access. You can try
the steps in the following sections.