If you can't use a program or service after you install Windows Live OneCare, or if the program stops working as expected, Firewall may be blocking the program or some of its components. To troubleshoot the problem, follow the steps below for the symptom you see.
Some programs require that you open a specific port or range of ports so that the program can send and receive information through Firewall. If this is the case, it will usually be noted in your program documentation. For more information about ports and how to open them, see Related Topics.