I too have a similar problem on a Windows 7 Enterprise machine running Dagent version 6.9.453 and a server running Deployment Solution Version 6.9 (build 453) Service Pack 4.
First off dagent's connection to the server is spotty at best, and takes about 16 minutes to even show up or connect to the deployment server as in
this unresolved issue. But it does eventually hit the server.
However like the original poster, any time I issue a job to the client computer from the server, it fails to execute and then the client disconnects from the server and lists the status as "Connection closed; session terminated." At this point, no further communication between client and server takes place until the client is restarted (and then it takes 16 minutes to connect.)
This is after I tried to create an image from this computer using sysprep. Despite the fact that it didn't successfully run, I now find this message repeated in the Dagent logfile. Which to me implies that Dagent is still waiting for the sysprep from a job that was long ago cancelled and deleted to run.
[08/02/2010 20:27:50.553 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:27:50.553 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:28:20.616 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:28:20.616 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:28:50.671 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:28:50.671 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:29:20.740 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:29:20.740 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:29:50.808 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:29:50.808 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:30:20.876 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:30:20.876 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
[08/02/2010 20:30:50.945 2144 1] WaitForSysPrep.cpp:44 - Image state is IMAGE_STATE_UNDEPLOYABLE
[08/02/2010 20:30:50.945 2144 2] DsAgent.cpp:625 CDSAgent::AgentCommand - QueryShutdownState
Again, any help would be appreciated. It's a pity there are so many issues on here that just get left to die without resolution, and it'd be nice if this didn't have to be one of them.