Yes, you should be able to re-enable Avast after you stop using AH. One thing, when you disable Avast make sure the game files within the settings folder (C:\Program Files\HTC\Aces High II\settings\) are not set to read-only! The way to check this is to right-click one of the files, select, "Properties," then check to see if, "Read Only" is selected. If it is, uncheck it and press OK. None of the setting files should be set to read-only.