There are know issues when applying this update on LCS/OCS Servers, as described in the KB974571 (MS09-056: Vulnerabilities in CryptoAPI could allow spoofing):
Services that are required by Communications Server are not started after you install this update and then restart a computer that is running any of the following versions of Communications Server: - Live Communications Server 2005 (LCS) - Live Communications Server 2005 SP1 - Office Communications Server 2007 Enterprise edition (OCS) - Office Communications Server 2007 Standard edition - Office Communications Server 2007 R2 Enterprise edition - Office Communications Server 2007 R2 Standard edition - Office Communicator 2007 Evaluation version only* - Office Communicator 2007 R2 Evaluation version only*
*The licensed production version of this application is not affected by this known issue. Only Office Communicator clients that are in their 180-day evaluation period are affected by this issue.
Until this issue is fixed, i recommend to not apply this KB on LCS/OCS servers.
*** Jerome Chout