Can anyone recommend a free antivirus now that AVG is malfunctioning?

[Nil]

For one, because it is bloated and it is known to cause problems.
I used Free ZA myself until it caused problems with my home
network. Uninstalling ZA was the solution. I replaced it with
Sygate Personal Firewall and my problems were gone.

That must have been several years ago. Sygate Personal Firewall hasn't
been available since about 2005, when it was bought up by Symantec. A
lot can change in five years.

I used ZA Firewall for a year after they offered a free years
subscription. I had no problem with it at all, and I found it to be
quite easy to use and had a good feature set. My subscription ran out a
few months ago and I didn't renew, but it wasn't because I found
anything wrong with the product.