Hello Brian,
Thank you for your message.
Please try using this
Microsoft tool that helps to automatically fix issues when you cannot update/install or fully uninstall software. You simply need to download the tool, run it and then follow the provided instructions.
Alternatively, if your Viewer was installed via the vanilla installer downloaded from our
website, then it might have been a false positive detection which sometimes occur - you can try submitting a
False Positive report to AVG, then add the Viewer installation folder to the antivirus exception list as described in
this guide and remove the *msi file from quarantine. Here's also a
full uninstallation guide that might be helpful if you want to install version 7 from scratch.
Please let us know if you have more questions.