Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv:1.9pre) Gecko/2008043013 Firefox/3.0pre Steps to reproduce: -> Was trying to get a DumpJSStack for my crash in Bug 431346 -> Open the Places Library - History -> Show all History -> Select a few entries (i think my case around 10) -> Context Menu -> Delete --> Crash i don't know why the Crash Data is different and not the same as https://bugzilla.mozilla.org/show_bug.cgi?id=431346#c13 the debug output shows the warning and then crash) (see the attachment for the complete data + DumpJSStack() WARNING: Attempting to register an observer twice!: file /debug/mozilla/toolkit/components/places/src/nsNavHistoryResult.cpp, line 3829 Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x00000001 0x140a868e in nsNavHistoryVisitResultNode::GetTime (this=0x15b4d350, aTime=0x1) at nsNavHistoryResult.h:429 429 NS_FORWARD_COMMON_RESULTNODE_TO_BASE (gdb) bt #0 0x140a868e in nsNavHistoryVisitResultNode::GetTime (this=0x15b4d350, aTime=0x1) at nsNavHistoryResult.h:429 #1 0x140a4040 in nsNavHistoryResult::OnEndUpdateBatch (this=0x15b42b30) at /debug/mozilla/toolkit/components/places/src/nsNavHistoryResult.cpp:4069 #2 0x14080ae8 in nsNavHistory::EndUpdateBatch (this=0x11de600) at /debug/mozilla/toolkit/components/places/src/nsNavHistory.cpp:3623 #3 0x1408bf11 in UpdateBatchScoper::~UpdateBatchScoper (this=0xbfffb66c) at /debug/mozilla/toolkit/components/places/src/nsNavHistory.cpp:263 #4 0x1408bf25 in UpdateBatchScoper::~UpdateBatchScoper (this=0xbfffb66c) at /debug/mozilla/toolkit/components/places/src/nsNavHistory.cpp:264 #5 0x14081c72 in nsNavHistory::RemovePages (this=0x11de600, aURIs=0x15fb6400, aLength=34, aDoBatchNotify=1) at /debug/mozilla/toolkit/components/places/src/nsNavHistory.cpp:3820 ....