Check the logs on your NS to see if there is any addtional acitivity occuring at the server level. It doesn't hurt to restart the Altiris service and the 2 dependent services.
Also, try running aexagentutil.exe /server:<yourservername> to reset the NS server for the agent. As stupid as this sounds it does fix the errors you are seeing your local agent log.
I've had mixed success when trying this thru RAAD, better success when logged directly into the resource in question and mixed success using a remote CMD like psexec.exe.