Not as helpful as planned

A few weeks ago my wife downloaded some free antivirus software, AVG I think, onto our desktop computer. She was hoping that maybe the reason it was running slow was from a virus and not because it needed more system memory. Well, it found a bunch of viruses, adware, tracking codes, etc. So she got rid of all that, but it was still having problems. In fact it started having more problems, the Internet took forever to load pages, and sometimes wouldn't work at all, even though our laptop Internet was working fine. So I had to take AVG off and that fixed it. At least we were able to use it for a little bit to get rid of the viruses that were on there.