Last weekend, with advice from this site, I sorted out playing DVDs on my new laptop with Win 8.1, a day later I suddenly lost all internet access, after a friend had a look at it, it turned out it was MacAfee Virus Checker.
Because I hadn't taken up their offer to take up a year's subscription after a month's free trial, it blocked access to the internet, once I removed MacAfee completely I got Internet back and downloaded AVG. Definitely some sneaky moves go on these days. So, if you get a new computer with a month's free trial. Beware.

I would always remove MacAfee free trials from any new
computer and put in AVG or Avast. Unless you want to
pay.

A virus checker checks viruses.
A firewall blocks internet access.

I suspect it may have been a virus and firewall in one and not to be confused with a anti virus program in its own right.

Pre installs do like to give you all the features so you get used to them and obviously loose them after the trial period.

What could also of happened is two anti virus programs running and clashing together which strangly cause a loss of connection.

Free Antivirus programs and Security are exactly what you pay for. Ive always paid for a decent security program for a firewall and anti virus.

It boils down to what your prepared to loose or personal data to have taken from your connected device.

Long term invest in decent security software. You dont have to pay the earth. My software normally retails at £45 but got it for £15 via ebay for 3 pcs.

Sorry for going on a bit. But ignorance is bliss.