I had the same problems. I suggest uninstalling and switching to Avira Personal. Sometimes it throws up a pop-up for a discount for the paid version, but never during a game.
I've had it for 2 years now, never had a problem. Still using it. If ur having problems to the point u want to turn it off to do stuff, then just go with another Anti virus software, and when u do, run a very thoroughly scan.
You cannot shut if off. The only way is to uninstall AVG free Ed. I never had any problems with it. Yeah about a month ago the promo ads that popped up were annoying but they went away.
I don't see why it would interfer with a steam games. I do know how ever if people get their games besides legit places(steam itself or a box from a store) they can sometimes come with trainers/bots/etc that a virus scan picks up as a trojan.
If AVG is taking up too many resources in memory, you need to upgrade the amount you have. I have 2GB and it hardly does anything to my resources. If anything expand your virtual memory you have.
pro:the easiest way to turn it of is to shutdown AVGTray application, press ctrl+alt+del, chose processes and close all processes starting with avg
con: if avg is your only antivirus and you turn it of your computer will be vaunerable for attacks.
tips: do not have more than one anti virus program installed to your computer. you may think this increases security... WRONG. it only increases the chance of virus attacks
I had a problem with AVG awhile back interfering with stream games. I think it is even listed on the steam support pages. Anyways uninstalling it all together fixed the problem. I have been using Avast anti-virus instead and it works great. It is free and I think it is an all around better program.