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Multiple anti-virus programs should not be running real-time scans together. They might conflict. I look at what you really need running on your computer.

I purchased a new computer, OS Windows 7. It came with Defender installed, also Norton on trial, but the trial is terminating very soon. I'm thinking of Security Essentials as a download, but I am concerned that it will conflict with Defender or AVG or other anti-virus software downloads. Will both work without conflict? Can you give me advice as to what is the best security for my computer that will not cause problems? Can Defender stand by itself or do I need to add another anti-virus program to my computer?

In this excerpt from Answercast #74, I look at some confusion around "Defender" and versions of Microsoft Security Essentials.

Multiple anti-virus programs

So this is a case where I believe Microsoft has done us a grave disservice in the way they've named things.

The "Defender" that comes with Windows 7 is, in fact, only an anti-spyware product. It is an anti-spyware scanner. So yes, absolutely - you do need something else in addition to that.

That's not true for Windows 8. For people who are reading or listening to this and thinking about Windows 8, Windows 8 comes with something called "Defender." And guess what? It is both an anti-spyware and an anti-virus program. It can pretty much stand on its own.

It is effectively "Microsoft Security Essentials" with a different name.

Microsoft Security Essentials

What I typically recommend for people in your situation (with your Windows 7 machine) is to download and install Microsoft Security Essentials.

That will automatically disable Windows Defender. It knows that Defender is going to be there; it knows that Defender is no longer necessary because Microsoft Security Essentials contains all of that functionality plus anti-virus.

It's a good replacement for Defender, and it will handle it transparently.

Duplicate malware programs

Now, as for the other anti-malware programs that you're talking about: Norton and AVG and so forth?

I typically don't recommend that people need all of them. I think one good solution is a great place to be. Microsoft Security Essentials is the solution that I typically recommend for people - and it's the solution I use myself.

Now, if you want to have Norton or AVG or something else on your machine, typically it's OK to have them there.

Clashing real-time scans

What's most important is that you not have any of their real-time scanning functions enabled.

It's not the presence of duplicate software that causes the problem, it's the attempt of more than one anti-malware product trying to do real-time scanning at the same time. That's when they can come into conflict.

This could do two things:

  1. It can cause false positives (where they'll both be complaining, or one or the other will be complaining about a problem that really isn't there);

  2. Or worse, they can interfere with each other's ability to detect malware - and malware will go undetected.

So, if you have those tools there, they're fine. You can have them. They're good for on-demand scans. But any of the automatic stuff? I would make serious attempts to be sure you've got them completely disabled.

My most serious attempt is to not even bother having them on the machine!

Microsoft Security Essentials, or AVG, or Norton? Just one of those would be a fine solution to getting your machine protected. I happen to recommend Microsoft Security Essentials.

Then, later, if and when you run into a problem, then you can take a look at saying, "OK, fine. I've got some malware on my machine somehow. Let's get an additional program or two to scan the machine to clean it up."

Those would be "on-demand" scans - without doing the real-time scanning that we know can cause a problem.

Anti-virus AND anti-spyware

So, ultimately, Microsoft Security Essentials will transparently replace Defender, which is exactly what you want.

Regardless of whether you use Microsoft Security Essentials or not, I recommend that you have one good anti-malware package (Microsoft Security Essentials or AVG or any of a number of others) to keep your machine protected.

You do not need to load up on multiple anti-malware tools at once. It will slow down your machine and potentially cause you a lot of false positives or worse - missed detection.

(Transcript lightly edited for readability.)

Article C6080 - November 28, 2012 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

Not what you needed?

Paul Masters
November 29, 2012 10:03 PM

Get rid of Norton. Uninstall it completely. (McAfee too, for those that have that hot mess installed.) Again, remove it COMPLETELY, then run CCleaner to get rid of all leftover traces. Then install one (and ONLY one) of several fine and FREE antivirus programs available. My personal recommendation is Avast!, but AVG is okay too, if a little bloated. McAfee and Norton are crap. As "that guy who fixes computers", I have seen those two programs cause more problems than they fix. Stay away from them.

November 30, 2012 12:19 PM

For folk who like to experiment, sandboxie is excellent & free.
It protects by throwing a barrier around your browser, then when you close the browser, everything is deleted,including any malware .It is possible to save outside the sandbox if required.

April Smith
November 30, 2012 9:42 PM

As to Paul Masters comment on "get rid of Norton"..years ago I never liked it either, but got new computer year ago & Norton came with my internet provider so decided to try it. It's been super so far but I use Malwarebytes (free version) also & run a full scan on that once in a while. But again, my Norton has not seemed to interfere with anything, not even ITunes updates, which can be really sensitive!

December 3, 2012 1:05 AM

I have never liked Norton OR McAfee, and had to stop using Avast! (which I did like, and used for years) because the new version stopped my PC from booting up.
Currently I have Microsoft Security Essentials and AVG on my desktop. They do their scheduled scans at different times, and do not seem to interfere with each other in real-time. If there IS a problem, 9 times out of 10 MSE will catch it. AVG just seems to repeatedly warn me about cookies.

One browser add-on I will mention, is Web Of Trust. That gives me a handy indicator whether a link is likely to cause issues before i go there, and gives me the opportunity to 'back out' if i end up at a site it doesn't like.

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