Microsoft recommends to postpone installing KB974571 on any LCS 2005 / OCS 2007 /OCS 2007 R2 servers.
“Microsoft is investigating this issue, and will determine the most appropriate way to address it. Customers who are not running OCS or LCS server are not affected by this known issue, and can safely ignore this issue.
Customers who have deployed the OCS or LCS product on a server should assess the risk that is involved to decide whether to install the security update on that server. These customers should revisit this Knowledge Base article often, because this article will be updated as soon as more information and a resolution are available.”