From c9's point of view, AVG is the worst anti-virus software out there and most anti-virus related support calls I field are about AVG which occasionally decides that because it doesn't know what c9 is, it must be bad, and deletes it. It may ask the user first, but most users will just instinctively click default behavior when frequently nagged about system level questions beyond their expertise as computer operators (which shows poor user interface design on behalf of AVG)
Turns out I am not the only one that thinks AVG is shit. IF you run AVG and Chrome, you are probably better off without any anti-virus at all. Go with trend micro or malwarebytes instead of AVG if you are shopping for anti-virus.
http://news.softpedia.com/news/avg-forcibly-installs-vulnerable-chrome-extension-that-exposes-user-s-browsing-history-498187.shtml