The Driver: %1 has encountered a communication error.
Please refer to Problem Determination Log for more details. For more information, see the Troubleshooting section of the online help.
The agent computer that the message specifies encountered a problem when trying to run a command sent from the workbench.
Check the error log for messages from the agent computer that the error message specifies. Click Window > Show View > Error Log.
Check the test log for any failures from virtual users. This message might be displayed when you add or remove users manually or by means of schedule stages.