There is a chance that you may have some Exchange 2007 servers that are not connected to the Internet. And by connected to the Internet I mean they can open the HTTP and HTTPS protocols. Although this is not a requirement for Exchange Server 2007, there are some issues with this configuration, namely some services may not start, such as:
- Microsoft Exchange Mailbox Assistants
- Microsoft Exchange Credential Service
If that's the case with your configuration and you already did some troubleshooting, you probably found some related information and maybe some hotfixes, such as the ones in the KB article 944752.
The easiest way to solve the problem is to edit the HOSTS file and then add the following entry:
127.0.0.1 crl.microsoft.com
This will prevent the CRL check from timing out (which also prevents the services from starting), instead it will make it fail (localhost rejects the connection), but the services will start.