If Mail Monitor server on a Windows NT system exits in an uncontrolled way while the PING scanning module is still running, it is necessary to reboot the system if you want to use the PING server again. The correct way to exit is to wait until any PING test is completed before stopping the server.
This problem usually occurs infrequently, but it can arise in three cases:
Note, however, that most PING tests are complete very soon after they start; depending on the network, a PING test to any one host should not last long. So any of these cases is more likely to arise if the PING scanning module's initialization file has a long list of hosts to check.
Workaround, to avoid rebooting your system
Modify the service startup (using the Services option from the Control Panel) to use a privileged interactive account, so that you can stop any ping.exe process that is suspended. Note that this account must be both privileged and interactive; the default non-interactive system account, for example, does not offer this service.