Running XP and FF23, my resource monitoring program (portable Apps: System-Explorer) shows during FF unresponsive periods that the RAM/Swap usage goes to zero (other indicators are normal). The Mouse & Keyboard are active but the time on my Start bar stops (seconds don't update for as many as 45 seconds sometimes). When FF recovers, the usage is restored. Usually, any mouse clicks that I input during that period all go off together (remembered and implemented). I only see this behavior when FF is running. All my queries about RAM/Swap return only cases where the usage is too high.