Exchange 2007 managed code services do not start after you install an update rollup for Exchange 2007 - due to Certificate Revocation List download failures

This problem can occur with more than just Exchange 2007. It can happen with anything that is .NET Framework based. The root cause typically is due to a proxy misconfiguration or if HTTP traffic in general on your Exchange server is severely limited.

To workaround the problem, check out KB 944752.