Nope, Mozilla didn't install those RadioWMPCoreGecko##.dll files, they were installed by a 3rd party plugin.

Thanks for replying edmeister. From the bit of research i`ve just done, it appears that "Gecko" is part of Firefox as it`s engine...according to this; http://www.useragentstring.com/Firefox9.0.1_id_19070.php

I don`t understand such things...and I hope I didn`t screw my Firefox after deleting "Gecko" keys in my registry!

If it`s a 3rd party file, I haven`t found a definitive explanation for it yet.

A user in this thread - https://support.mozilla.org/en-US/questions/878063 - say that file is part of a "WeLoveMusic (Or something like that) toolbar".

Here - http://regrunreanimator.com/research/download-managers/%C2%B5torrent/radiowmpcoregecko19-dll.htm - is says it is part of a uTorrent toolbar. Also, it is probably part of other Conduit Toolbar add-ons, a sketchy organization (my opinion) that was once banned from the official add-ons website.

It probably has "Gecko" in its' name because it was made specifically for Gecko-based browers, and maybe to make users think it is a useful file, instead of a DLL file which is closely aligned with Malware. Somebody who is getting that "message" from Norton needs to run a search (For Files and Folders) in Windows and tell us exactly where that file is located (as I requested in the first link I posted), so we can maybe figure out what installed that file.

I read the other replies you linked to. Here`s it`s route; E:\Documents and Settings\Barry\Application Data\Mozilla\Firefox\Profiles\knr3vdtj.default\extensions\{915793b2-0a75-4c84-8ed7-479086c6d84e}\components

I do have a 3rd party toolbar from "Nirsoft"that I got from the Firefox site a long ways back...and it updates itself as a Firefox add-on/extension soon after. It has a net radio and net tv section built into it. The tv vid player app uses WMP. The toolbar uses it`s own GUI for the radio section.

Funny though, "Conduit" is also in that folder...but it appears to handle the search engine feature of the toolbar. I never see adverts or blocked popups...but I have to say, it`s really a strange thing when you see the Norton pop-up....and you know it has dloaded that same xxx19.dll many times over the last 2 weeks. That`s just too weird.

That is a component added by an extension.
You can open the install.rdf file in that extensions\{GUID} folder to see to which extension it belongs.