MS Exchange Server 2013 SP1 contains a bug which causes the transport service not being able to start if 3rd party agents (like DisclaimIt) are installed, because MS Exchange Server 2013 SP1 messed up assembly redirection for the public assemblies by providing invalid formatted XML-files.

This problem has already been acknowledged by Microsoft and is described in the following KB article: KB2938053 

This KB article also describes how to fix the problem.

-Franz