When you try to change your Windows Firewall settings, the options are greyed out and you can't make any changes.
To fix this, follow these steps:
Click the Start button, then type Windows Firewall in the Search box.
Click Windows Firewall, and then click Allow a program or feature through Windows Firewall.
Click the Change settings button. If a User Account Control window appears, click Yes, or enter your user name and password, then click OK.
You can now make changes to your Windows Firewall settings.
Note: If the Change settings button is still greyed out, your administrator may have disabled the option for you to change the settings. Contact your administrator for help with this. If you are the administrator for the computer, restart Windows and log in with your administrator account, then follow the steps above.
For more information about Windows Firewall, visit: http://windows.microsoft.com/en-US/windows7/products/features/windows-firewall
For more information about User Account Control, visit: http://windows.microsoft.com/en-US/windows7/What-is-User-Account-Control
For more information about administrator accounts, visit: http://windows.microsoft.com/en-US/windows-vista/What-is-an-administrator-account