The only difference I see between your system and mine is the fact that I use the
Windows firewall and you're using Comodo's firewall.
I have no problems and conflicts and you do. Is is possible that the firewall or parts of the Comodo
firewall are interfering with avast! 
I did a format of the system and the first application I installed was Avast. Comodo firewall was not installed at that time and I got a BSOD repeated until I removed it from safe mode.
