Running Avast! 6 and Microsoft Security Essentials Simultaneously - *really* a problem?

Hello, I know it's "bad" to run two anti-virus programs simultaneously, but, in all honestly, is it *seriously* a problem? I've had Avast! 6 and MSE running simultaneously in the past and experienced no problems. Since then I had a little (unresolved) issue with Windows 7 freezing on wake, but I've run every diagnosis possible and there is no way that Avast 6 / MSE caused the issue (pretty sure it's a Bios/Driver issue); I did a Factory Restore of Windows 7 and I've re-installed MSE and am about to re-install Avast! 6.


Anyways, in the past I've had Avast! 6 stop Trojans from loading on malicious web-ads while browsing on Chrome that MSE did nothing about, but I've also had a virus that was already running and installed on my system that MSE caught and destroyed while Avast! was unble to detect it... basically I want to keep both.


Again, I've had the two running in the past simultanesouly and noticed no major change in performance (CPU at an average 15% - Pentium Dual Core; 4 GB RAM at an average 40%). Is it really dangerous to run the two simultaneously?


And if the two do conflict and screw up my PC, could they cause any serious damage that (worst case scenario) a "Factory Windows 7 Restore" wouldn't fix? Please don't give the standard "It's a bad idea to run two," rather, if you're going to say so, please explain why in terms of known Avast! / MSE conflicts.


Thanks in advance for all answers!



Also, at the Avast! forums they're pretty chill with running MSE and Avast! together:


Please thoroughly review the following:

Microsoft Security Essentials - Installation Checklist and FAQ 

Please carefully note this from the above checklist:

Can I have more than one real-time anti-malware product installed?

No.  Having more than one real-time anti-malware product installed will compete with other anti-malware product(s), and can cause severe performance problems and system instability issues, and may limit the effectiveness of the products installed.  Even if you attempt to have more than one product installed, with one active and another disabled, the disabled product will likely still have active components and/or drivers installed that will conflict with MSE.  The important issue here is that any other product with real-time scanning will conflict with MSE (or any other real-time product).


Then do what you want to do.  You're certainly forewarned and obviously know it's not recommended.  


If your computer hoses up or gets infected because neither AV program is working properly and you're hunting a cause you can look in the mirror instead of blaming Avast and/or MSE....while you woudn't do that, trust me - there are plenty of folks who will blame the AV program. 


And no, using two or more AV products will not cause a problem that cannot be resolved by reformat/reinstall and as long as you don't mind doing that proceed full speed ahead and use whatever programs you wish to use.


By the way I use Avast 6 and MSE.  But on different computers.



MVP Consumer Security 2014-2016
Windows Insider MVP 2016-2018

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Last updated October 6, 2020 Views 17,835 Applies to: