Dan,
Not sure what sure what may have caused it (perhaps an unsuccessful save of the NetMonitor View), but exit out of any NetMonitor or NetConfig GUI’s and then rename the monitor_dflt.mvw file to something else (i.e. monitor_dflt.mvw.backup). Then bring up NetMonitor and let it re-build the monitor_dflt.mvw file for you.
Hope this helps.
Jim Cobane
Henry Ford Health