If you are using Mozilla Firefox, you might have noticed that its built-in download manager scans the downloaded file for virus or spyware upon completion.

Actually this kind of behavior only occurs under Microsoft Windows OS because it uses the antivirus software installed in your Windows to scan the file. If no anti-virus software is installed, it'll not scan the file.
Sometimes it might become annoying for you and you would like to disable this automatic scanning as it takes a few extra seconds to scan the file and it also causes following problems to a few users:
- The built-in download manager freezes while downloading a file.
- It doesnt download a file and gives warning message: "Blocked: Download may contain a virus or spyware", even you are sure that the file is completely safe.
So in this tutorial, I'll tell you how to disable this automatic virus scanning to get rid of these annoying problems.
1. Open firefox and type about:config in the addressbar and press Enter. It’ll confirm, click on I’ll be careful, I promise! button.
2. Now type scanwhendone in the Filter box. It'll show a single entry "browser.download.manager.scanWhenDone" in the results window.
3. Either double-click on this entry or right-click on it and select "Toggle". It'll set its value to "False".

4. That's it. You have done. Now Firefox will not scan any downloaded file and you should not face any freezing problem.
This article was posted by VG in following section: Mozilla Firefox, Troubleshooting.
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ztnetzhopz
Thanks for the help. let's spread the word.
Giannakis
very useful!
before i saw this article, i typed "about:config" and at the search bar i typed "scan", to see if any setting was available.
it was, but i needed reassurance of what to do, so i checked this post and helped me.
thanks!
Farthen
Yeah, let's spread the word and disable another useful security feature!!! It's like UAC. Well....... nevermind.
VG
^^ lol. I can understand what are you talking about but as I mentioned in this tutorial, there are a few problems related to this new feature. So if one face this problem, he can fix it by following this tutorial. :)
felicia
THANK YOU! I've been looking around at Mozilla forums and haven't been able to find it. Who knew it was that easy!
batchi84
THANK YOU! very much VG "vishal"
very useful!
shivoy
hey..dis trick really works..thnx vishal..m already a big fan of urs.!!
such gr8 tweaks ..very useful indeed..by d way i wanted to know that which theme is this which is being displayed on dis page...it really cool!!
shivoy
i mean the theme visible thru the screeenshot of firefox 3 download manager.
VG
^^ Its AeroVG theme for Windows Vista.
who?
Thanks for the help VG. This has been causing lock-ups on me recently. I'll be happier now I don't have to worry about it.