Microsoft has updated their KB974571 with instructions on how to resolve this problem when you apply the security update:

--> http://support.microsoft.com/kb/974571

A fix that resolves this issue is available for download from the Microsoft Download Center. To obtain the fix, visit the following Microsoft Web page:
http://go.microsoft.com/fwlink/?LinkId=168248 (http://go.microsoft.com/fwlink/?LinkId=168248)

This fix works for both clients and servers, and it is applicable to the following roles for all versions of Office Communications Server and Live Communications Server 2005 SP1 and for evaluation versions of Office Communicator:

• Standard Edition Server
• Director server role
• Enterprise Edition Consolidated
• Enterprise Edition Distributed – Front End
• Edge Server
• Proxy server role
• Office Communicator 2007 Evaluation version only
• Office Communicator 2007 R2 Evaluation version only
• Office Communicator 2005 Evaluation version only

To run the fix, type the following command at a command prompt, and then press ENTER:
ocsasnfix.exe

This fix can be applied either before or after you install security update 974571. If you apply the fix after you install security update 974571, we recommend that you apply the fix before you restart the computer. If you already restarted the computer after you installed security update 974571, this fix can still be applied. However, the Office Communication Services must be started manually.

If all services start without any issues, this indicates that this fix has been applied and is working correctly.

This fix sets the OCSASNFIX DWORD value to 1 for the following registry subkey on the OCS 2007/R2 and LCS 2005-SP1 Server:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\RtcSrv\InstallInfo\OCSASNFIX

Additional known issues with this security update

When you deploy the Standard Edition role on a new installation of any version of Office Communications Server, activation fails if security update 974571 is installed. To resolve this problem, apply this fix, and then run the activation again. 

Sincerely,
Tonino Bruno | ICT Consultant | Pro-Exchange Community