I don't use anti-virus stuff - not on my work machine programming - absolutely not on daw machine.
 
#1. 4 years ago I started using internet usb stick kind of modem, and had this hang of taskbar for a couple of minutes in between activating internet. Thought it might be virus.
 
I tested a range of the most common antivirus, Norton, Kapersky, McAfee, AVG, Avira, PCTools and still one or two. Without exception these softwares caused more problems than my thought of virus. Machines were slow responding and made my machine perform like my first PC 1985 - 10MHz something. Tried all kinds of settings to disable stuff - but they still intervened more than I wanted. Some had serious bugs too, suddenly hanging the app running(AVG if some internet url parsing was active). Ran these for the trial period or shorter then uninstalled.
 
Looking further into my issue, turning off just about all software that were claiming internet looking for updates - it was basically not a problem anymore. Windows Automatic update service disabled, Flash player, Adobe Acrobat etc - turned off - and this hanging changed from every time booting up, to a couple of times a week only. So it's just something with how this usb stick drivers were hooking into tcp/ip.
 
Now switching to wireless broadband as separate router through wired network card - never any problems with this.
 
So still not running any antivirus.
 
#2. 15 years ago I think I got some kind of virus - browser and activeX controls something. I suddenly had some issue visiting a site. I had at the time two identical Windows NT 4 machines, and identified a file in system32 folder and copied from the other machine - and it went away and worked normally again.
 
So I took the chance to send the failing file to a couple of antivirus software companies - a report of possibly unknown virus. None showed any interest to investigate this at all.
 
This leads to same conclusion as OP - antivirus companies create these viruses because it's good for business.
 
So for me two good reasons not consider running antivirus software. It's basically a scam based on a problem that do exist - but is really minor compared to what antivirus software do to your system. Just some basic care when clicking on things - and you are fine.
 
Easiest way to control people and make them your slave - scare them. That is basically what antivirus companies do - make you pay annually(most of them). Since a payed service must be better than free, right?
 
I don't know, just my view of it all....

No anti virus / anti malware program is completely foolproof.
 
I had some adware lurking away on my laptop and neither MSE or Malawarebytes (full version) picked it up.
I ran an online scan using Trend Micro? That worked but then other stuff will get past Trend.
 
I don't have any A/V installed on my DAW, I only ever connect to the internet when downloading music related stuff and always disconnect as soon as I've finished.
 
 

No anti-virus on main and backup DAW ...
 
I use anti-virus on office laptop that runs email and handles all downloads. Anything clients bring on USB sticks / send via mail or dropbox goes through that laptop ...
 
Got paranoid once after years without "protection" and installed anti-virus prior to doing a big bunch of online updates, scanned everything thoroughly but only found the "usual" threads that (I suspect) anti-virus programms always list to justify themselves
 

FreeFlyBertl
 
... but only found the "usual" threads that (I suspect) anti-virus programms always list to justify themselves
 

 
Yes, that is a funny part.
 
I ran Microsoft something malware removal tool, since my xp cannot run Security Essentials anymore.
Shortly after starting a full scan - it reported an infected file - so I let it continue - must see what this might be. After 9 hours running, pretty high cpu - fans blowing their brains out - it was finished and was reading three infected files. But final report said - no infected files found - and empty report.
 
What was that about...
 

I used to use System Mechanic Pro and still have a current license but found it a resource hog. I did like the additional utilities included which I bought into - optimisations, defrags, cleanings stuff, blah blah. However, apart from it slowing things down more than it sped things up, the virus protection was reported as being pretty average. So I tried Iobit's System Care, which had a cool interface and had Bit Defender Virus protection, generally reported as being pretty good...only problem, BSOD when using CC...every time I tried to upgrade or install something. 
 
So now, after listening to some advice from a member, I'm just using Microsoft Security Essentials...seems to do the job, can upgrade via CC, low resource usage and it's free...not bad.
 
PS...I don't work for MS.

Norton here, and no problems with it at all.
 
It certainly used to cause problems, which is how it got it's reputation, I think.
 
Nowadays I have it running all the time, and never caused a glitch.  This machine is connected to internet most of the time, and has not had any viruses so far.
 
I read all the Norton horror stories, and look, puzzled, at my machine running smoothly, and wonder if I am just incredibly lucky..

If you ran a mail server which accepted all incoming mail addressed to your domain you'd pretty quickly find out how many viruses (more accurately, trojans) there are out there. A huge proportion of spam carries a trojan payload, often concealed as an invoice or form to fill in.

The last time I saw an attempt to infect one of my machines was four years ago when the MS security application went berserk when I was reading a very reputable website indeed. Presumably the site had been hacked and instructions to automatically download and run a rootkit and trojan loader inserted into it. A website I run had an attempted hacking attack around the same time.

The time before that was a freshly installed XP which connected without me intending it to before the firewall was enabled. It attracted the attention of a worm in under a minute (botnets scanning the internet for open ports were the method of transmission).

Take an unprotected PC on line and you are taking a risk. The majority of malware out there nowadays is intended for the purpose of obtaining remote control of your PC for spamming and other purposes, much of it originates in Russia and the far east. The infection rate from hacked websites etc. is lower than it used to be because MS in particular has taken security much more seriously over the last decade and gradually closed holes that allowed buffer overun exploits and implemented proper user account level security.

As for the effectiveness of MSSE/Win8's defender, I have a collection of nasties acquired over the years and it picks up all of them as soon as they launch and blocks them before they can run. Not all commercial anti-virus applications are as effective.

I use the Microsoft Security Essentials (called Defender in Win 8/8.1) and a paid version of Malwarebytes.  It does not cause any DPC Latency and does not interfere with Sonar.
 
I do part-time PC support and all my clients, except one, use Microsoft and Malwarebytes as I recommend and they are not having any security issues.
 
For e-mail, I use "Mailwasher Pro" to filter out what I want blacklisted (blocked) or considered spam and using that, the e-mails never get to my e-mail program.
 
 

Viruses are unfortunately not a thing of the past. A few weeks ago, virus was introduced at one of my client's office that cost literally 10's of thousands of dollars to clean up. Some of the software engineers there used to not run AVS on their home computers because "they never got a virus and only went to safe web sites". They do now.
 
That said, not all AVS is the same. I avoid Norton and McAffee. They are almost as bad as a virus, they are so intrusive. At the present, I'm running Avast on 7 computers and it is "OK". I disable it on the DAW when I'm doing something with a lot of VSTs. I also run scam now and then with MalwareBytes. 

Over the years I've used three anti-virus applications. McAffee in the 90s then I abandoned that when it grew into an all-consuming monster that required more configuration, maintenance and watching than everything else put together.

So I switched to kaspersky, only to see that contract feature-bloat and swell into another all-consuming monster over a few years.

Nowadays I just use Windows Defender with Sonar and everything else DAW related (including .wav files) and in the other boot environment Photoshop-related put in the exclusions list. The system load is so light I literally can't tell any difference whether it's on or off and it correctly identifies my ever-expanding collection of trojans, root-kits, key-loggers and assorted nasties the spam-bots see fit to email to the world.