I recently noticed that on Windows, my Firefox (version 16.0.1), hangs whenever a new download is started or a download is complete.

So, I did some exploring online and discovered that there is actually a quick fix for this faulty behavior.

The Fix for Firefox Hanging on Download Start/Complete on Windows

Delete the file “downloads.sqlite” in “C:\Users\YOUR_WINDOWS_USERNAME\AppData\Roaming\Mozilla\Firefox\Profiles\YOUR_FIREFOX_PROFILE_NAME.default\“.

To apply the fix, you need to first close Firefox, then go the suggested folder, find “downloads.sqlite” and delete it. Then start Firefox and test how it behaves with downloads.

No hangs should be present and Firefox should run smoothly.