Windows Firewall: recommended links
A firewall can help prevent hackers or malicious software (such as worms) from gaining access to your computer through a network or the Internet. A firewall can also help stop your computer from sending malicious software to other computers.
If you’re having trouble allowing other computers to communicate with your computer through Windows Firewall, you can try using the Incoming Connections troubleshooter to automatically find and fix some common problems.
Open the Incoming Connections troubleshooter by clicking the Start button 
, and then clicking Control Panel. In the search box, type troubleshooter, and then click Troubleshooting. Click View all, and then click Incoming Connections.
