You might be aware of the fact that Firefox 3 provides automatic virus scanning of downloaded files on completion of download. This feature works only when your system has an Anti Virus program installed. Though this feature may be useful but the scanning of downloaded files may be annoying as it puts extra load on system and it is not that necessary as most anti virus softwares provide real time monitoring and protection.

If you would like to disable this automatic scanning then follow along:

1. Type about:config in your browser’s address bar.

2. Find browser.download.manager.scanWhenDone. Its default value would be true.

3. Double click on it to toggle its value to false.

This will disable automatic virus scanning in Firefox 3.