OCS and 0x80090302

When working with an Office Communicator Service 2007 installation I came across the error message 0x80090302 when using the tracing tool. This error message appeared on the back end server when authenticating over the Internet.

after some research we found the reason to be a lockdown group policy that requires NTLMv2. By changing the following policies in the we made it work.

Policy	Setting
Network security: LAN Manager authentication level	Send LM & NTLM - use NTLMv2 session security if negotiated
Network security: Minimum session security for NTLM SSP based (including secure RPC) clients	Enabled
Network security: Minimum session security for NTLM SSP based	Enabled