Here are some of the things that got me.

Check the dsm.opt file on the client and make sure its pointing to the right
server.  Also make sure it can resolve the ADSM server using the same server
name specified in the clients dsm.opt file by pinging it from the client.  The
service will sometimes crash if it cannot resolve the ADSM server.  Some of my
NT clients just couldn't resolve for some reason and I had to point them to an
ip until the server team "gets around" to fixing them.   Also stop and restart
the NT scheduler service and then check the dsmsched.log file that gets written.
That can tell you whats going wrong.  Lastly check the NT Event viewer.

Jack