Perhaps try Avast for antivirus? I run Avast and Comodo concurrently, with no problems at all, and I've been using Avast for my AV program for the last 6 or so years and had -0- infections on any of my machines thus far. The home version of Avast is free, just requires an email registration once every 14 or so months (and they don't spam your email), and it updates all the time but without the need to buy a subscription. I've never had a complaint with it.