You install Lync 2010 on a computer that has the Conferencing Add-in for Microsoft Office Outlook installed.
In Outlook, you create a conferencing request that uses the Live Meeting service, and then you click the Online Meeting button. This changes the conference to use Lync 2010 Online Meeting.
In this scenario, the Presenters button and the Options button for the Conferencing Add-in for Office Outlook are still available in the Outlook ribbon. However, these two buttons should not be available in a conferencing request for Lync 2010 Online Meeting.
To fix this problem, install the following cumulative update:
2433228 Description of the update for the Live Meeting Conferencing Add-in for Outlook: November 2010
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.