Hello Alain,
I'm sorry to hear about this. May I know which AVG program you have installed on your computer (AVG Free Antivirus or AVG Internet Security). You can disable AVG components (open AVG > Free Antivirus/Internet Security > menu > settings > components) and check if you can download Google Earth.
Best regards,
Alok.
Thank you for the information Alain,
I request you to change AVG Firewall network profile to private (open AVG Internet Security > menu > settings > components > firewall > customize > network profile > change all the network public to private), please go to Firewall customize settings again > scroll down > click on system rules > enable all the system rules if it's not configured, please click OK and check if you can access/download the Google Earth with enabled AVG Internet Security. If you still not able to find components option then please share a screenshot of the AVG menu/settings options. You can check the following link to see the instructions about taking the screenshot (http://support.avg.com/SupportArticleView?urlname=How-to-create-a-screenshot).
Best regards,
Alok.
AVG Guru