Disable virus scan in Firefox

When you download a file with Mozilla Firefox 3, it starts to scan the downloaded file for malicious code or virus etc. This is available only for Firefox versions 3.0 and above and only on Windows. But this is pretty useless behavior for computers on which you already have a good antivirus installed as most modern antivirus software automatically scan any newly created file. Some antivirus products like avast! (http://www.avast.com/) and NOD32 (http://www.eset.com/) even scan all the web traffic, therefore scanning all downloaded bytes automatically. You can disable this scanning behavior of Mozilla Firefox using the instructions below :

1. Run Mozilla Firefox.
2. Type about:config in the Firefox address location bar (where you type web site address).
3. Click on the I’ll be careful, I promise! button when prompted with warning dialog as shown :
   
4. In the Filter textbox type browser.download.manager. You would see preference list filtered as shown in the picture :
   
5. In the preference list, double-click on browser.download.manager.scanWhenDone preference name. This would change its value to false from the original default value of true.
6. That's it. Now when you download a file, Firefox wont scan it.