Well I used Avast Free and Comodo firewall before I upgrade to Avast Internet Security and I didn,t have any problems,so you can use Avast and Comodo firewall easilly,but why did you disable Avast firewall,you pay for AIS licence and now you are using other firewall,if I were you I will remove Comodo firewall and use only Avast firewall (AIS) of course it,s your choice.