Hi Barry, I don't know if anyone here can answer these questions any better than you can. 1) For some reason, Firefox didn't finish shutdown during the allotted time. According to the "App Notes" line, it seems to be related to the "Clear history when Firefox closes" feature: OMTP- xpcom_runtime_abort(###!!! ABORT: file resource:///modules/Sanitizer.jsm, line 152) 2) The Mozilla Crash Reporter is a separate program (crashreporter.exe) , but I don't know how it is triggered. Conceivably extending the shutdown time has broken some assumption that enables close coordination between the shutdown watchdog process and the crash reporter. 3) If clearing Offline Website Data from time to time completely avoids this problem, that's interesting. However, I don't know how to determine what in particular causes the hang. Perhaps someone familiar with what is being cleared could look at a snapshot of certain files at that point to figure it out. > Is there a setting so that FF does not save OWD? I couldn't tell you authoritatively, but if you are experimenting... I notice the preferences related to offline data are named as follows in about:config: * privacy.clearOnShutdown.offlineApps * privacy.cpd.offlineApps There's a preference named '''offline-apps.allow_by_default''' that you could double-click to toggle from true to false and see whether that makes any difference. I don't know what sites will be affected, but it should be much less problematic than disabling DOM storage. 4) No idea.