When the Windows Management Instrumentation (WMI) service is paused in System Center 2012 Configuration Manager, the SMS Agent Host service (CCMExec.exe) becomes nonfunctional. After the WMI service is restarted, the CCMExec.exe service is not automatically restarted and remains nonfunctional.
This problem occurs because WMI cancels all requests when it is paused and does not restart those requests when the service is resumed or restarted.
To work around this problem immediately, manually restart the SMS Agent Host service. The periodic client health check will also detect that the SMS Agent Host is not functioning and restart it when it executes.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.