This indicates that the vmware probe has lost the port that it listens on (48***). Usually when you see this message it means a probe has become unresponsive and/or crashed. If everything looks like it's working, and the probe is responsive, I wouldn't be too concerned as long as the error doesn't keep coming back.
If it does keep coming back, check to see if the probe has been crashing; make sure you're on the latest versions of the probe and robot/controller; and check to make sure any Antivirus software is set to exclude the Nimsoft folder.