My grandson is playing Steam games with Avast Internet Security v17.2.2288 without issues. So far, he has played 11 different games. The problem isn’t necessarily Avast, but perhaps a conflict between Avast, Steam and something else on your computer.
Possible. The issues started after the update though (i use avast since roughly a year and haven’t had any issues so far), and i haven’t installed any new software lately.
If there are known issues between steam avast and something else, i’d love to know about them.