I believe that the client has a printing caching functionality that runs on a schedule when the client is open. There used to be issues with some printer drivers causing crashes. You could try to disable this functionality and see if connection configuration works. If it does, launching of applications might still trigger the issue, so at that point your best solution would be to contact support so that they can instruct you on how to collect the necessary data to investigate the issue.
(fyi: To change the setting manually: open the client but do not configure anything, head to "tools > options > advanced", scroll down and disable "cache printers ..." / "refresh printers ..." options then close and reopen the client. If the registry is an easier way, when I changed these settings, the values of "PrintRefreshCache" and "PrintUseCache" in "hkcu\software\parallels\appserverclient" were changed from "1" to "0".)