› Tech › Browser, Date, Firefox Back Date Of Your System Can Crash Firefox I was in trouble for few days, when at the time of shutdown I started getting a popup which has the title "nsappshell:EventWindow". I googled it, and had found very little info about this. My system used to crash very badly. It even freeze the Task manager. Somehow I realized it may be Firefox, which I always use. It was not closing when I closed it. It resided in task manager. Then, I searched again for firefox 3.01 crash and found that Firefox can crash when system date is in back.