OS: Kubuntu 18.04 KDE Plasma Version: 5.12.7 KDE Framework Version: 5.44.0 Qt Version: 5.9.5 Kernel Version: 4.15.0-50-generic OS Type: 64-bit Firefox: 67.0 (64 bit) Problem: in the last couple of months, every so often (i think every couple of week, or so) Firefox freeze my entire system. It happens randomly, doesn't matter what website I'm browsing. Nothing responds, absolutely nothing, and I'm forced to reboot the system. When the system reboots, I restart Firefox, does not matter if I chose to start a new session or restore the previous one, after a few minutes the same freeze happens. And I'm forced to reboot. After a freeze, if I delete the history and cookies, Firefox is going to freeze again after a few minutes. So far, the only work around I have found is to create a new profile, and let Sync doing the rest of the job. This however is only a workaround, it does not stop Firefox to eventually freeze again the entire system. As I told you before, after a couple of weeks (top) it freezes again. Is there any way I can understand why Firefox freezes my system?