Are you running AVG from a safe mode boot ?? -- the virus may be blocking AVG from actually running -- best bet is to download a new copy of AVG from the internet along with an updated definitions file to a thumbdrive - boot into safe mode - install the new copy of AVG and run the scan again (the safe mode boot should keep the virus from loading itself so that AVG can properly get rid of it (IIRC AVG can run in safe mode but if not use Spybot search and destroy to do the same ! - It's free and does a good job removing most virii )
Run malware scanning tools like MalwareBytes to try to have the tool remove it. Also if you found it with your scanning tool, go ahead and quarantine it immediately and then run other tools to try to clean up any other things you might find.e
I would still recommend using Avast and their preboot scan. I have seen things that malware bytes and spybot search and destroy have left behind picked up in a preboot scan of Avast. So might be something to think about.