But if I have DX11 (as required for Windows 7) CC should not install old version. And why You think alert is caused by DirectX files?
Dx9 is required for CC to run, so obviously its installed, otherwise the program wouldn't run.
I too have Avast installed, and the sandbox feature kicks in from time to time. It has nothing to do with the antivirus. The sandbox is there for programs you aren't sure about.
I'm sure about MY GAME, but my PLAYERS (maby) not. That's the point. If alert shows only on my PC I will ignore it, but I tested it on 3 difference PC/notebooks.
When I enable/disable some python files [when exporting to exe] for few exe avast show alert. And that is not caused by one exe (example my game). I try it on examples from CC and still had alert.
I will just warn about fake alarms (caused) by avast in description of my game.