HI
I will let Chris answer but I think Firefox does not work as well as other browsers with MM. I use Chrome and it works well.
james
thank you, james.
some info for Chris:
I may install Chrome for this ad-hoc purpose, but I've been faithful to Firefox (Netscape Communicator) since using MacOs 7 Classic.
other hardware that may be implied is a brand-new TP-Link N750 Wireless DB Gigabit TL-WDR 4300 which I've been using in wired mode only (so far), and a brand-new Cat5e _ 7,5m. Intellinet Networking Cable for the intranet set-up.
I'm planning to install a (brand new, again) WD 3TB MyCloud for NAS storage.
then, for wireless, (brand new, yes again!) a laptop Asus X555L i5 8Gb ram - which is not yet operative.
current computer which is running Firefox 42.0 is a desktop tower featuring an AsusTeK© P-67-Sabertooth motherboard, i7-2600 CPU @ 3,40GHz, 8.00GB installed RAM, 1TB WD Black internal storage, Windows 7 Ultimate (64Bit).
really I'd like to know what's happening before NAS setup ...
___ maybe, just *maybe*, my playlists are just too long ...

___ the complete Frank Zappa or Miles Davis discography for example.
Firefox 42 has only a few add-ons (Extensions) installed, and since long ago didn't prompt this type warning, surely since Flash issues were solved.
not ever since then ... but if everything points out to Add-Ons issues, I would uninstall some of them without regrets ...

thank you,
fernando.