It appears to start with Firefox versions above 40. All versions up to but not including 43.0.3 were subject to Mozilla tightening up on Certificate security. This seemed to affect some computers more so than others. It showed up in various ways:
- Firefox would not load a Google site of any shape or form and displaying a message that Google was untrusted, or other messages that meant the same thing including invalid Certificate.
- Firefox would exhibit similar behaviour with other sites like Adobe.
- Version 43.0.3 appears to have addressed that problem.
It seems as if neither company talks to each other, or does any compatibility testing before releasing version updates. One blames the other, and no one does anything positive to rectify.
There is however one thing that you can do - ditch Kaspersky in favour of Bitdefender Internet Security. OK - you will lose money if Kaspersky's subscription has some time left - but is the aggravation worth whatever dollars are left? I think not, and the reason why I switched security programs.
No more problems with partial protection when doing Internet banking etc. Bitdefender has a similar function that does work, it runs within the Bitdefender program as a sub function, therefore no reliance on browsers that act up from time to time.
As a related point - Bitdefender Internet Security performs as well as, and better in some aspects than Kaspersky Internet Security in lab testing.