We have the following issue: Microsoft Firewall failed. The failure occurred during Initialization of reverse Network Address Translation (NAT). because the configuration property of the key SOFTWARE\Microsoft\Fpc\Arrays\{C871D159-A75E-4453-8E40-291F6397C1FE}\Publishing\PNATServerMappings\{371B7DA0-8496-4731-823F-CF35182B2913}\ClientSetsExcluded could not be accessed. Use the source location 2.546.3.0.1200.166 to report the failure. The error code in the Data area of the event properties indicates the cause of the failure. For more information about this event, see ISA Server Help. The error description is: The system cannot find the file specified. We are trying to fix this as per these instructions: Dom: The error is generated only if you are publishing any servers. It is looking for a registry key called "ClientSetsExcluded" which it simply does not create when you create the publishing rule. To fix it go into the properties of every one of your published servers and click the "Applies To" tab. On that tab there is an "Exceptions" area. Add a dummy client set to the exceptions. Hit ok and wait a few seconds, then go back in and remove the exception. Adding and removing the exception creates the registry key that it is looking for and the errors stop. To check that the registry has been successfully look in the event viewer, make a reference of the number after PNATServerMappings, go the in the registry, look for the matching number and see if ClientSetsExcluded has been created under the number. For example for the above error I would make a reference of {E1F6B393-EF5A-4870-FF9-0AFA3DAFBF9D}in the event viewer and see if ClientSetsExcluded has been created under it in the registry and then move to next occurence of the error in the event viewer. When ever I try to do this I get : 'List Cannot Be Empty'. I have tried to recreate the entries to no avail. Any help is appreciated!