I am aware of this one: https://support.mozilla.org/en-US/questions/997796 - but I do not have AVG installed. Every time I launch Firefox, even into a blank tab page, a few seconds later my bandwidth starts being used. I have Cucusoft Net Guard installed, and TCPEye, and both show that Firefox is connected to the internet and downloading - even if I have not loaded any page , it still remains on "new tab" ... I do have FDM too, but this happens with or without it running (ditto with my localhost XAMMP installation.) I have disabled all add-ons, and run Firefox in safe-mode, yet the same thing happens: the moment I start a new tab, my bandwidth gets murdered (side note: my normal surfing via Telkom Mobile internet is sloooow between 60Kbps and 250Kbps if I'm lucky, but this background downloading is off-the-charts at over 1200Kbps and within seconds I've lost over 20MB of really really expensive mobile internet, which I simply cannot afford to waste, which is why I have all these TCP monitors and network graphs running the whole time.) I have also run a Kaspersky rootkit revealer and it reports no threats. I have ZoneAlarm anti-virus and firewall which also reports no infections (ditto ClamWin)