Download Malwarebytes instead and run that. Antivirus is like a Dr, you don't get the Dr. to help you stop getting SPAM Faxes or Junk Mail in your mailbox do you? That is what Malware is, the 'junk' stuff adverts to get you to do things that make them money in someway, so Antivirus doesn't 'see it' as it doesn't 'damage' files normally just 'trick you' into doing things.
Secondly what Antivirus are you using. If you say 'the one that came with the computer', unless you regularly pay for the subscription which gave out 30days later, it is useless. I would suggest removing the Antivirus (and not sure about your Adwcleaner, I never heard of it before and wary on some of them) and try Avira, AVG or Panda , all are free and are highly recommended by their success rates.
All utility files like these can be found on www.filehippo.com, listing the latest version to make it easier for you.