Philip’s blog talks about the case of the missing DHCP
Amy talks about why this happens:
Why DHCP Stops Working After You Add a Custom Access Rule – SecureSMB:
One of the unusual-ness of SBS is the behavior of rule making on the box it’s protecting. This is one side effect we see, and in particular I’ve seen it pop up post sp2. ISA is very RFC aware and my guess is that with the application of sp2 it’s gotten a bit more RFC aware than it already was. But that’s pure speculation and probably what is going on is the mere ‘change’ that a service pack application brings and perhaps teh consultant has changed rule order post sp2 and is not equating that with the action. But bottom line, watch your rules. I don’t have a special DHCP rule here and my server works just fine.