Yes, specifically FF that causes the problems. Kaspersky said one or more of the plug-ins/Add-ons had caught them out since they'd been written differently in a late FF issue. Something like that.
It may be this happened when I loaded FF for 10. Not sure, but certainly about that time. Come to think of it, a W7 laptop started to throw wobblers with FF about the same time. I've put the same Kasper file on both.
My Kasper for Android worked for days, then suddenly there was an unequivocal warning that FF would not be acceptable as the browser. I killed the App but am assured I will be able to reload FF soon. Kaspersky would not turn green during this period.