Dear Sirs Good evening, Since April 27, 2017 my notebook has crashed 4 times and this had never happened before. It all starts after I'm usually browsing with a message up there in the left corner of the screen telling me that Mozilla Firefox is not responding. Then with 4 or 5 clicks everything will crash until it locks the mouse cursor and freezes the screen. Without option I had to force the laptop to shut down. On the last day 03 May 2017, I uninstalled and reinstalled Mozilla 53.0 again, but before yesterday it crashed again. Could anyone tell me what's going on, and what should I do to prevent this from happening again? Has the notebook been attacked by some pest not detected by the antivirus? Config .: Windows 7 Mozilla Firefox since January 18, 2014 Norton Internet Security I look forward to a contact. Thank you, Jose Sery