You don't specify the OS of your PC. I have Windows 7 64bit Home Premium. Per the image below.
I've used MalwareBytes. But who knows where you retrieved MalwareBytes from. If what you retrieved is not viral software then what is the issue with running it?
With regard to Avast I had a friend with that installed and all kinds of adware and even viruses were on his PC, mostly due to him. But you have to wonder what Avast gets out of giving away free software of that type. That's alot of R&D plus keeping
virus definitions up to date. Oh some friend of his wifes told them Avast is AWESOME and FREE. As far as I could tell it certainly didn't perform its job.
Microsoft for Windows 7 and Above has
Microsoft Security Essentials which is/are free. I believe that comes installed with Windows 8 and above.
I had a friend who bought Kapersky anti virus. Basically worth more than his PC. I took it back to Wal-Mart and got his refund for him and then downloaded Microsoft Security Essentials or whatever onto his PC. I wouldn't bother with buying 3rd party software
for that. It certainly didn't help SONY with regard to North Korea did it (although that was an inside job apparently since North Korea somehow was provided user names and passwords for accessing SONY's systems or something and no doubt China was in Cahoots
too. After all you gotta figure China loves NK shooting ballistic missiles towards Japan. I'm certain that most of North Koreas hackers were trained by China or maybe Chinese hackers were in North Korea doing that since it's difficult to believe Kim Stupid
Dirtbag, the fearless leader of North Korea, would allow his minions to have knowledge way above that idiots capability.)? You would've thought the NSA would've stopped any of that from happening with SONY in the U.S. but they're probably too busy violating
every American Citizens rights by Presidential Order against the Constitution and Bill of Rights to do their freekin job like prior to 9/11. Americans spying on Americans. Isn't life AWESOME! Reminds me of the KGB or maybe the NAZI's spying on their own people.
Except the Americans at the NSA violate all other American citizens and their own rights for money (666 baby).
I mean if Microsofts Security Essentials can't detect viruses, etc what's the point? Shouldn't Microsoft know how to protect their own software if anybody should? Although after the fact I suppose MalwareBytes may be good to run.
Usually nothing piles up on a system unless the systems owner is clueless about the system. Which for the majority of people means "I can click here and do stupid things on my computer and everything will be OK!". I know peeps that download, install
software, no idea where it came from or anything, disregard where during the install it will install adware, popups all kinds of things.
As Ron White says "You can't fix stupid". I mean most people know when to change wiper blades on their car and not to put diesel fuel in a tank for gasoline. But when it comes to computers
it's almost like they have zero clue. And don't even want to learn anything. So they get what happens.