I have a Microsoft exchange 2007 server installed on windows server 2008 where the exchange server information store service has begun to fail. It is due to dependency services not starting. The dependency services are related to Microsoft Forefront. I have removed all instances of forefront from the registry in the past and then performed a re installation and gotten the exchange server working again. In this case, removing all instances of forefront from the registry has not helped. I am still getting the error. I have tried to install Exchange 2007 SP 2 as a response to this, and I am receiving an access denied error when it reaches the hub transport service. Any assistance with this would be invaluable.