In the Windows Control Panel, Uninstall a Program, I suggest also clicking the "Installed on" column heading to review installations chronologically. You may find an unrecognized or suspicious items with an unexpected name that also needs to go. (Be wary of anything with protect or safeguard in the name, like search protect, browser safeguard, etc.)

To discover the physical location of a plugin, you can type or paste about:plugins in the address bar and press Enter. This will load a page showing all your plugins and the types of content they handle and where they are on disk. Firefox actually finds most of these through registry entries, but also checks some shared folders, so if it's in a shared folder such as one of the following, I think you can just delete it:

• C:\Program Files (x86)\Mozilla Firefox\Plugins
• C:\Program Files (x86)\Mozilla Firefox\browser\plugins

(I mean delete the plugin file, not the whole folder...)

By the way, some extensions have the ability to hide, so it can be useful to test searching in

Firefox's Safe Mode

This is a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled (Flash and other plugins still run)

In the dialog, click "Start in Safe Mode" (not Reset)

Any improvement? Please check the Extensions section of the Add-ons page to see whether anything new is appearing and if it can be removed.

If the problem still occurs in Safe Mode, you may want to check:

Connection Settings

By default, Firefox will connect using IE's settings, which I think are the same as Windows' settings. Please check both of the following:

(A) Firefox

orange Firefox button (or Tools menu) > Options > Advanced > Network mini-tab > "Settings" button

The default is "Use system proxy settings" but try "No proxy"

(B) Windows

Either in IE or the Windows Control Panel, call up the Internet Options dialog. On the Connections tab, click LAN Settings. If anything is checked here, make a note of it, then try unchecking everything.

Any difference?

Plugins also can hide in other places.

• https://developer.mozilla.org/Add-ons/Plugins/Gecko_Plugin_API_Reference/Plug-in_Basics#How_Gecko_Finds_Plug-ins

Thank you