If you or the PC owner is sure that they have not being messing the the group policy editor or the registry then this could be a sign that there is some malware at work here.
So make sure you have done a full Virus scan and malware scan - if you are unsure as to what to use see
"What are Good Virus/Spyware?Update/Firewall Practices?" faq779-5240
That aside you can check the group policy for the firewall by clicking on Start > Click Run > type gpedit.msc > Click OK
This will open the group policy editor.
Following taken from
Configuring Windows Firewall Group Policy
Contact your network administrator to determine if a Group Policy setting prevents programs and scenarios from running in a corporate environment.
Windows Firewall Group Policy settings are located in the following Group Policy Object Editor snap-in paths: • Computer Configuration/Administrative Templates/Network/Network Connections/Windows Firewall
• Computer Configuration/Administrative Templates/Network/Network Connections/Windows Firewall/ Domain Profile
• Computer Configuration/Administrative Templates/Network/Network Connections/Windows Firewall/ Standard Profile
From these locations, you can configure the following Group Policy settings: • Windows Firewall: Allow authenticated Internet Protocol security (IPSec) bypass
• Windows Firewall: Protect all network connections
• Windows Firewall: Do not allow exceptions
• Windows Firewall: Define program exceptions
• Windows Firewall: Allow local program exceptions
• Windows Firewall: Allow remote administration exception
• Windows Firewall: Allow file and print sharing exception
• Windows Firewall: Allow ICMP exceptions
• Windows Firewall: Allow Remote Desktop exception
• Windows Firewall: Allow Universal Plug and Plan (UpnP) framework exception
• Windows Firewall: Prohibit notifications
• Windows Firewall: Allow logging
• Windows Firewall: Prohibit unicast response to multicast or broadcast requests
• Windows Firewall: Define port exceptions
• Windows Firewall: Allow local port exceptions
Greg Palmer
Freeware Utilities for Windows Administrators.