Hi,
I was experiencing a couple issues in our OCS R2 environment. These issues were:
I noticed that a new Office Communicator patch was released in July 2009. It can be found at: http://www.microsoft.com/downloads/details.aspx?familyid=515D6DBA-4C6A-48BB-A06A-D99C5742676D&displaylang=en.
After downloading and installing the patch, both of the above issues were resolved!!
Along with this patch, patches for Live Meeting and the OCS server were also released:
So, if you're encountering some weird Office Communicator behavior and it looks like your configuration looks good, download the patches to see if they resolve the issue.