Open up Resource Manager for CCSRISK12 and go to Summaries > Processing Summary. When is the Most Recent Event Time? If this is old, the client isn't reporting and you can probably delete it to clean things up.
Once you clean up all the systems that haven't reported in awhile, you'll want to either work to make sure everyone has the client, or keep an eye on who stops reporting and try to find out the cause.
Look to imaging, manual reboots, or certain problem employees as the cause of Altiris Agent removal. You'll want to also check Policies to make sure you aren't accidentally causing this on a particular subset of computers.