Hi, please try to download full installation file instead of download manager:
If installation still doesnt work please try to use remover tool prior to installation:
Have a Toshiba laptop running Vista, using either IE or Firefox. No problem downloading AVG, but when installing, get an error message saying update has stopped working and posts another message saying that there is a connectivity issue "The AVG setup is not able to detect a working Internet connection. Please make sure that you are connected to the Internet and click Retry to try again." and I am connected (via wireless connection) to the internet when I get the message (otherwise I would not have been able to download). I have my Firewall turned off and the security settings to allow download.com.