Do you have a Security software suite that includes a Firewall ? Most
if not all disable the Windows Firewall to use it's own. If the service is
stopping or timing out you'll likely find a Event Log entry in the System
Event log. Windows Firewall has dependency services so it may be a
issue with other related services.

System Event Log:
Click Start, Run (type) EventVwr.msc [Enter]
Expand the System Log in the Left pane and check the Right Pane for
red icons that denote errors.