If you install Exchange Server 2007 SP3 on a Windows Server 2008 R2 all-in-one server, you may get an error during installation of the Hub Transport role. The error says,
A timeout was reached (30000 milliseconds) while waiting for the Microsoft Exchange Protected Service Host service to connect.
The Microsoft Exchange Protected Service Host service failed to start due to the following error: The service did not respond to the start or control request in a timely fashion.
This happens because there is a dependancy in the Microsoft Exchange Service Host service on IPv6. Check to ensure that Internet Protocol Version 6 (TCP/IPv6) is enabled on the properties of the network adapter.