Windows XP Service Pack 2 enables firewall by default. To prevent firewall enabled after installation, apply the registry setting BEFORE install SP2. Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsFirewall] [HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsFirewallDomainProfile] “EnableFirewall”=dword:00000000 [HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsFirewallStandardProfile] “EnableFirewall”=dword:00000000