Agent Not On Machine But Altiris Thinks It is

Hello,

We have a couple of "active" assets that had the agent manually removed.  When looking at the console through Manage Computers, Altiris displays the machine as having an agent installed.  The machine no longer has has an agent.  How can we get Altiris to properly display the machine in the console as Not Having An Agent (Unmanaged). 

Thanks,