Why does the ping command not work after Service Pack 2 is installed?
Windows XP Service Pack 2 enables the Windows Firewall by default. The ping command works by sending Internet Control Message Protocol (ICMP) requests. For security reasons, Windows Firewall defaults to dropping all ICMP requests, and thus pinging a computer with Service Pack 2 installed results in a "Request timed out" message.
To enable ICMP requests for ping to work on a computer with Windows XP Service Pack 2 installed, use the following steps.