A firewall is designed to prevent unauthorized access to your computer or home network. XP includes its own firewall component called Internet Connection Firewall (ICF). Once ICF is enabled, it will by default prevent access to any shared folders on your computer or network. You can make some adjustments the firewall settings to permit access to your shared folders.

In order to accomplish this, you must complete the following steps:

1. Open the properties dialog box for your Internet Connection.

2. From the properties dialog box, select the Advanced tab.
3. Click the Settings button.
4. From the Services tab, click Add.
5. Type in a description for the service definition such as File Sharing.
6. Type in 127.0.0.1 for the IP address and 445 for both the internet and external TCP ports as shown in the figure.
7. Click OK and place a check beside the new service definition.

If your shared folders are still not accessible, repeat the above steps for ports 135, 136, 137, and 138.