@ the OP: just don't take into account all the bs they told you on Comodo forums about "two firewalls", ie, neither the Network shield not the Web shield are firewalls, and they do not conflict with any firewall
my god seems these guys there have absolutely no idea about avast "free" components
I've used Avast 4 & 5 a long time together with Comodo firewall&def+...no issue whatsoever.
As to your DCOM exploit issue, it could be FPs from the network shield, you need to give more details about the sites you visit when the avast alerts come. As to why Comodo Internet security doesn't stop those, it's their problem. But again, if you got FPs, that's another story.