CIS has incompatibilty issues with Symantec AntiVirus 10.1.6.6000, 10.1.7.7000 & 10.1.8.8000 (Corporate Edition)....
I reported this about 1 year ago, & to the best of my knowledge it has not been fixed to this date.... Roberta
Hi Roberta,
Can you please provide more detailed information about you the setup.
OS ; Service Pack & platform (32bit or x64) in the 1st place.
Are you using just Comodo Firewall or full CIS Suite with Anti-Virus and you want one of the Anti-Viruses being on-demand only?
If that is Comodo Firewall only – that has to be looked at by developers very seriously.
If you have 2 AV the situation is different. The conflicts can occur even if you set one of the AVs being on-demand only.
There are few threads and advices here in the forum about KIS, for example, and how to set that up. BitDefender 10 requires few additional tricks in order to avoid conflicts … and so on...
I managed to test and set up many working together. I have 5 different AVs/Anti-Malware on- demand scanners currently working perfectly all together with my main AV, and other security layers
I did test Comodo AV too, but decided – “that's not the one” (it is not present here now here)
But the main thing is that even if all seems to be set up correctly there still could be clashes when just 2 AVs are present.
(Offtopic! 
) The Symantec is a very special one. - I would not allow this thing being installed on a clean computer... with or without any other security alongside ever! ( my personal opinion... forget about it 
)But
the main questions remain:
you PC configuration & whether you are using Comodo AV or just Firewall only?
The reference to previously reported troubles, as you pointed, would be helpful as well.
My regards
Author