I run OCS 2007 R2 in a Windows 7 environment with Office 2010 package. Servers run Server 2008 R2.

Recently 2 of my users reported that other users were seeing them as Presence Unknown. When I searched for their details in Communicator they appeared fine, but when I added them to my contacts in Communicator they became Presence Unknown. Closed and reopened Outlook and Office Communicator, then they reappeared as Available. Logged off and logged back onto my account and they were instantly showing as Presence Unknown again. I've checked event logs on OCS Servers and there are no events triggering for this issue. I have recently started logging events on the workstations of the users affected by this issue and hope to find a fix but need to get this resolved immediately as they deal with both internal and federated users.

Can anyone assist?