It appears the memory leak in Firefox is back. I do know there have been issues between Firefox and Norton in the past and there may be again. The current version of Firefox is 54.0.1. Norton indicates it is current. OS is Windows 7 32-bit. Watching through the task manager Firefox keeps grabbing more an more memory. At some point the PC will lock up, usually when an attempt is made to open a new tab. The only way out when that happens is a restart. Usually when it appears Firefox is becoming too bloated I just restart it.