Free security isn't really your best option, Its best to use software that will first clean the computer and then once the computer is clean, install an anti virus, myself i use bullguard which is good. but its mostly on what you prefer.

A lot of antivirus software such as Norton, are very useless if someone knows how to spread a virus with it FUD.

I recommend using malwarebytes. [ Register or Signin to view external links. ]

For adware and such, I would also use adwcleaner.

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Be careful of any kind of freeware on the internet. Malwarebytes is a very good tool in my opinion, and you can quarantine all of the infected files on your computer after the scan is done.

If this does not fix it all, PM me with exactly what is happening to your computer. In the end, sometimes it is just easier reformatting your hard drive sometimes than hassling with viruses that you don't know how to get rid of.

Hi.

To start, you can use the following to attempt to remove them:

MalwareBytes Anti-Malware

Run a full scan using that,
next:

Use Comodo Firewall
This is NOT an anti-virus, this is a firewall, most of the time viruses are either Bitcoin miners, Botnet software or RAT software.
Comodo blocks these connections and alert's you to take action against it.

If you're looking for a good anti-virus, not just a firewall,
You'll probably want to look into ESET nod32 (cracked).

EDIT:
Just a side note,
Look into SandBoxie for running .EXE files in, [ Register or Signin to view external links. ]

Hope I helped.