That topic is also over a year old, so wouldn't be for the version you are using right now.
Unfortunately I don't use the AIS version or a gamer, so I can't be any practical help.
Personally I would still suggest a clean install to make sure you have a clean start.
Check the behavouor shield log and see if there are any game files listed and try adding them to the behavior shield, expert settings, trusted processes.
C:\Documents and Settings\All Users\Application Data\AVAST Software\Avast\report\BehaviorShield.txt (XP) Or (C:\ProgramData\AVAST Software\Avast\report\BehaviorShield.txt)
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It is almost 1:30am here and I'm calling it a night, hopefully someone in the same time zone can pick up on this.