The IOC for h1cam18 was not running properly, an old image was being displayed and centroid values were frozen.  Tried restarting the IOC, it didn't clear the problem.  Tried rebooting h1digivideo1, it came back OK, but the IOC for h1cam18 wouldn't run.  Tried deleting all of camera 18's log files and restarting, still wouldn't run.  Logged on to network switch to power cycle the h1cam18, then restarted the IOC and it appears to be behaving OK now.