To help provide security for your Windows XP SP2-based computer, Windows Firewall blocks unsolicited connections to your computer. However, sometimes you might want to make an exception and permit someone to connect to your computer. For example, the following scenarios describe occasions when you might want someone to be able to connect to your computer:
You are playing a multiplayer game over the Internet.
You are expecting to receive a file that is sent through an instant message program.
After you install Windows XP SP2, client applications may not successfully receive data from a server. Following are some examples:
An FTP client
Multimedia streaming software
New mail notifications in some e-mail programs
Alternatively, server applications that are running on a Windows XP SP2-based computer may not respond to client requests. Following are some examples:
A Web server such as Internet Information Services (IIS)
Remote Desktop
File Sharing
XP SP2 Compatibility Issues
MS KB Link
It's not me, it's someone else.