For some reason an internal 3ds Max process reports this error when tyFlow is present. It appears to be benign and can simply be ignored. Since the message is not reported by tyFlow itself, the exact source of the message is unknown.
This large error message popup can appear on machines that do not have the 3ds Max root directory added to the system PATH environment variable, for whatever reason. Adding the 3ds Max root directory to the system PATH environment variable manually should suppress the error.