Symptom
You computer is clearly connected to the Internet, but an alert box with this message appears when you attempt to use the Software Update control panel in Mac OS X:
"Software Update is not able to connect to the Internet."
A similar message may appear for Sherlock or when using Mac Help to connect to the Internet.
Solution
You can work around this by connecting to www.apple.com in a Web browser before using Software Update, Sherlock, or Mac Help.
Alternatively, you could use the Network Utility included with Mac OS X to ping www.apple.com before using them.
Your Internet service provider or network administrator provides a DNS server that converts names like "apple.com" into their numerical IP addresses. Apple has identified certain DNS servers that may provide Software Update with an unexpected response, producing the alert described above.
Installing the Mac OS X 10.0.2 Update will prevent this issue.