Clients Inactive in Ghost 3.1 Console

I have installed Ghost 3.1 server/console on a Server 2008 R2 with Windows 7 clients.  Currently I have 150 clients installed.  Several days ago all the clients were showing up as active in the console.  Then I noticed some were showing inactive.  Currenlty I have only about 40 of the 150 that are showing active.  All the clients are online and most being used.

I have have reinstalled the Client Agent via the console to all clients and the successfully completed however most are still not active.  I have gone to several of the inactive clients and the Altiris Deployment Agent is running, but still not active.

Any suggestion on why they would be inactive and what I might do to correct the problem.

Thanks in advance,

Art W.