It is a new crash signature in the trunk. It is #108 top crasher in 4.0b9 for the last week. Signature js::mjit::ic::BasePolyIC::releasePools() UUID bbe93bc3-7666-4578-a02e-ca3db2110117 Time 2011-01-17 08:20:30.563125 Uptime 63762 Last Crash 146311 seconds (1.7 days) before submission Install Age 146292 seconds (1.7 days) since version was first installed. Product Firefox Version 4.0b9 Build ID 20110110191547 Branch 2.0 OS Windows NT OS Version 6.1.7600 CPU x86 CPU Info AuthenticAMD family 16 model 4 stepping 3 Crash Reason EXCEPTION_ACCESS_VIOLATION_WRITE Crash Address 0x2000 App Notes AdapterVendorID: 10de, AdapterDeviceID: 0615 Frame Module Signature [Expand] Source 0 mozjs.dll js::mjit::ic::BasePolyIC::releasePools js/src/methodjit/PolyIC.h:287 1 mozjs.dll js::mjit::JITScript::purgePICs js/src/methodjit/PolyIC.cpp:2773 2 mozjs.dll JSCompartment::purge js/src/jscompartment.cpp:476 3 mozjs.dll PreGCCleanup js/src/jsgc.cpp:2261 4 mozjs.dll GCUntilDone js/src/jsgc.cpp:2725 5 mozjs.dll JS_GC js/src/jsapi.cpp:2547 6 xul.dll nsXPConnect::Collect js/src/xpconnect/src/nsXPConnect.cpp:407 7 xul.dll nsXPConnect::GarbageCollect js/src/xpconnect/src/nsXPConnect.cpp:415 8 xul.dll nsJSContext::CC dom/base/nsJSEnvironment.cpp:3630 9 xul.dll nsThread::ProcessNextEvent xpcom/threads/nsThread.cpp:649 10 xul.dll mozilla::ipc::MessagePump::Run ipc/glue/MessagePump.cpp:134 11 xul.dll xul.dll@0xb20297 12 xul.dll MessageLoop::RunInternal ipc/chromium/src/base/message_loop.cc:219 13 xul.dll MessageLoop::RunHandler ipc/chromium/src/base/message_loop.cc:202 14 mozcrt19.dll _VEC_memzero 15 xul.dll xul.dll@0x35dcad 16 firefox.exe firefox.exe@0x1bb7 17 ntdll.dll WinSqmSetIfMaxDWORD 18 ntdll.dll _RtlUserThreadStart 19 firefox.exe firefox.exe@0x186f 20 firefox.exe firefox.exe@0x186f More reports at: http://crash-stats.mozilla.com/report/list?range_value=4&range_unit=weeks&signature=js%3A%3Amjit%3A%3Aic%3A%3ABasePolyIC%3A%3AreleasePools%28%29&version=Firefox%3A4.0b9

This seems to now be Instantbird's #2 crasher (and should be moving to the #1 crasher, if we fixed it properly...), related Instantbird bug: https://bugzilla.instantbird.org/show_bug.cgi?id=1247 Crash reports: http://crash-stats.instantbird.com/report/list?product=Instantbird&query_search=signature&query_type=exact&range_value=1&range_unit=weeks&do_query=1&signature=js%3A%3Amjit%3A%3Aic%3A%3ABasePolyIC%3A%3AreleasePools%28%29

In Firefox, it's a low volume crash. The stack now looks like: rame Module Signature [Expand] Source 0 mozjs.dll js::mjit::ic::BasePolyIC::releasePools js/src/methodjit/PolyIC.h:187 1 mozjs.dll js::mjit::JITScript::purgePICs js/src/methodjit/PolyIC.cpp:3260 2 mozjs.dll js::mjit::ic::PurgePICs js/src/methodjit/PolyIC.cpp:3275 3 mozjs.dll JSCompartment::sweep js/src/jscompartment.cpp:561 4 mozjs.dll SweepPhase js/src/jsgc.cpp:2313 5 mozjs.dll MarkAndSweep js/src/jsgc.cpp:2406 6 mozjs.dll GCCycle js/src/jsgc.cpp:2649 7 mozjs.dll js_GC js/src/jsgc.cpp:2735 8 mozjs.dll JS_CompartmentGC js/src/jsapi.cpp:2616 9 mozjs.dll JS_GC js/src/jsapi.cpp:2623 10 xul.dll nsXPConnect::Collect js/src/xpconnect/src/nsXPConnect.cpp:415 11 xul.dll nsXPConnect::GarbageCollect js/src/xpconnect/src/nsXPConnect.cpp:423 12 xul.dll nsJSContext::GarbageCollectNow dom/base/nsJSEnvironment.cpp:3189 13 xul.dll nsTimerImpl::Fire xpcom/threads/nsTimerImpl.cpp:424 14 xul.dll nsTimerEvent::Run xpcom/threads/nsTimerImpl.cpp:520 More reports at: https://crash-stats.mozilla.com/report/list?signature=js%3A%3Amjit%3A%3Aic%3A%3ABasePolyIC%3A%3AreleasePools%28%29

JM is gone.