Hey bridgecobbler,
This is an issue we are aware of but unfortunately do not have a clear solution to. We do know the issue is not caused by Perfect Vermin itself but instead an interaction with another program most often the users antivirus. Most users who have suffered from this issue have been able to get around it by making an exception for Perfect Vermin in their antivirus.
Hopefully that helps,
-Maceo (Game Designer/Game Artist)