i know Avast is ok . but i like free software
While some types of free software are OK (example, VLC Media Player), it's best to stick with a paid AV/AM solution. I use a ESET Smart Security on some, Emsisoft Internet Security on others, and most has Malwarebytes Premium Lifetime licenses, where I stocked up when on promo as a second layer of protection.
With free solutions, most ships with some type of catch, be it pop-up advertising, getting emails for promos constantly (that are recurring subscriptions), another reason why I grab one year/3 PC's on promo. Some may be as old as 2013 versions, though all one has to do is download the latest one, and use the enclosed key to activate. Then I enjoy peace of mind, in fact, I have 3 unused ESET Smart Security for 1 year/3 PC's unopened, yet still will be good.
I get Emsisoft Internet Security (3 PC's) for free by continually referring others where allowed, though did pay for the first year over three years back, that's a lot of folks taking up my referral link.;-)
One thing that I do suggest, and it's 100% free, is download the Emsisoft Emergency Kit, it can be extracted & installed to a USB Flash drive, if it's the only item on it, a 4GB one will do. Then one can scan every computer in the house that's running Windows, one may be surprised at what'll be found, will remove PUP's, known bad registry entries & more. The good thing is that as long as any file will fit on the drive, will be quarantined, one reason why 8GB models are the 'sweet spot' today & really costs no more than 4GB models when on promo, sometimes 3 for $10 shipped. No, they're not the fastest, yet gets the job done, and I've never had one to go bad on me, though have had a couple to sprout legs.
I had a gut feeling whom the suspect was, only there were two, not just one. The first was my wife's son, who grabbed another, loaded with quarantined Malware files from at least a dozen computers & bundled to look like games. He paid the price by becoming infected as soon as the drive was inserted, though didn't realize until too late.,and eventually brought both he took back to his mother when I wasn't here. The other was an in-law, it was the same deal, only he traded it for two packs of cigarettes at a store within sight of his home. He paid the price with the butt kicking of his life, my mother-in-law threated to sue, but the store owner showed her the Flash drive & knew it was mine, as I had used it on her computer several times. That got him a few more whacks in the head with a broom for stealing.;-).
Anyway, since the good old days when Avast was a top dog, back when it had the auto stereo look, and also featured a great boot time scanner, once MSE first hit the scene (& was also great for a year or so), their software has gone downhill. For me, free doesn't cut it, though I do admit to having MSE on one Windows 7 install, with MBAM Premium as a active backup. It's the only one I've had that doesn't nag.
Cat