Sadly, v8 is a total mess and I quickly switched over to Avast which is really excellent.
The problem with almost every antivirus is that it leaves behind files on your computer. These files may interfere with the new antivirus program you are uninstalling.
Fortunately, AVG provides you a remover utility that will cleanly remove itself from your computer.
AVG Remover utility removes all parts of AVG installation on your computer, including registry items, installation and user files on your disk, etc. AVG Remover is the least option to be used in case the AVG uninstallation / repair installation process has failed repeatedly.
All AVG user settings will be removed after the uninstallation, as well as the Virus Vault content and other item related to AVG installation and use.
Have you used this?