Assume that a time skew exists between a Microsoft Lync Server 2010, Group Chat server and the Group Chat database. In this situation, the time that displays for all messages in the Group Chat client is incorrect. Additionally, the messages do not display in order.
This issue occurs because the algorithm that is used to compensate the time skew is incorrect.
To resolve this issue, install the following cumulative update:
2500447 Description of the update for Lync Server 2010 Group Chat: April 2011
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.