I've been getting the same message since the first time I shut the program down and opened it again. Each time I have had to reinstall the program which is exceedingly time consuming. Let me know if anyone comes up with a useful solution.
Try to pause antivirus for a few seconds on both server and workstation, and then start Proseries on the workstation. it might work. you need to then update antivirus to ensure Proseries 19 is in the Trusted applications list. Hope this works!