Schedule Shutdown with failed status

Dear Forum,

I'm having problem with Schedule Shutdown, i have been monitoring this situation since upgrading from version 7.2.34 to version 7.2.39 (21/09/2011). Using version 7.2.34 the schedule shutdown running smoothly, after upgrading to version 7.2.39 the schedule shutdown is failed in the same day for almost all agents with remarks "Connection refused: connect" or "Agent is not reachabable". After restarting the Desktop Central server the schedule shutdown running smoothly, but i'm having this problem again every week and i have to restart the server.

Today the problem is appears again after the server last restarted 6 days ago with the same remarks "Connection refused: connect" or "Agent is not reachabable", although yesterday the schedule shutdown running smoothly.

Thanks & Regards