The problem has been resolved.
Now all browsers including Google Chrome may be used to download PVTmaster with no difficulties.
Thanks to feedback from several users, the technical team for PVTmaster has encountered a minor incompatibility of the download page with the Chrome internet browser by Google. The error message can be disregarded using the "keep" option in this case. This could be a temporary solution to the problem while we keep working with Google to address the issue.
In the meantime we do recommend that users download the software using the internet browsers Mozilla Firefox or Internet Explorer for the best download experience.