Kaspersky Internet Security 2013 has been released into the market. And almost at the same time Firefox launched its latest stable version 15.0
As of now, although no major conflicts have been reported by users on online forums, but a glitch is crashing browsers for some users as soon as they enable the Kaspersky plug-ins for Firefox.
Firefox remembers the last page/tab opened by you. So if the last page that remained in the browser was the permission page generated by Kaspersky Internet Security, then the browser closes itself (may be it is trying to restart the browser).
The moment Firefox opens and before it closes again automatically(within a second), hit "CTRL+N". That will open a new tab and it will remain in the memory of Fireox from now on. And you can work normally.