only if it (norton) have registry protection ON. if not, it's not an issue (still it's only what i thinkin, and it can be something else)
hum .... what u can do, it's check the event's. u can find it in controll panel -> admins tools. and one more thing .... try to install lates .net frimework. after this, reboot and try install comodo again.
u can check the pc with hijackthis tool. after scan, u can remove some suspicious stuff. if there are not instaled, or ther remove some time ago.
one more thing. what if u have to many connections in network connection ? coz this can be an issue as well. yes i know this sound stupid, but u never know ;p ... what i'm trying to say, it's if u have other vpn like software, let's say hamachi/wippien/kali, try to remove it (add/remove software) then reboot and try to install comodo.