This bug was filed from the Socorro interface and is report bp-34a5aaf9-7e84-4a2b-a473-1085e2121012 . ============================================================= Seen while looking at 16.0.1 crash reports. Currently sitting as #2 crash with no bug attached, so filing. This has been around in other releases as well. https://crash-stats.mozilla.com/report/list?signature=hang%20|%20kernelbase.dll@0x115e8 Some correlations: hang | kernelbase.dll@0x115e8|EXCEPTION_BREAKPOINT (2606 crashes) 13% (351/2606) vs. 7% (4664/64824) {635abd67-4fe9-1b23-4f01-e679fa7484c1} (Yahoo! Toolbar, https://addons.mozilla.org/addon/2032). Frame Module Signature Source 0 ntdll.dll ZwWaitForMultipleObjects 1 KERNELBASE.dll KERNELBASE.dll@0x115e8 2 kernel32.dll kernel32.dll@0x1162c 3 user32.dll RealMsgWaitForMultipleObjectsEx 4 user32.dll MsgWaitForMultipleObjects 5 NPSWF32_11_4_402_287.dll F_1152915508___________________________________ F_685430368_________________________________________________________________________________________:115 6 NPSWF32_11_4_402_287.dll F2166389_____________________________________________________________________ F_1410520652_____________________________________________________________________:509 7 NPSWF32_11_4_402_287.dll F_917831355____________________________________________ F_1410520652_____________________________________________________________________:445 8 NPSWF32_11_4_402_287.dll F1315696776________________________________ F_1410520652_____________________________________________________________________:409 9 NPSWF32_11_4_402_287.dll F81047063_______________________________________ F_569578941____________________________________________________________________________________:180 10 NPSWF32_11_4_402_287.dll F845925699_____________________________________ F_566823266______________________________________________________________________________________________:92 11 NPSWF32_11_4_402_287.dll F1703203432____________________________________________________ F_2034658840_____________________________________________________________________________________________:537 12 NPSWF32_11_4_402_287.dll F_2071852363___________________________________________________________ F_2034658840_____________________________________________________________________________________________:1795 13 xul.dll mozilla::plugins::BrowserStreamChild::Deliver dom/plugins/ipc/BrowserStreamChild.cpp:236 14 xul.dll MessageLoop::RunTask ipc/chromium/src/base/message_loop.cc:326 15 xul.dll MessageLoop::DeferOrRunPendingTask ipc/chromium/src/base/message_loop.cc:334 16 xul.dll MessageLoop::DoWork ipc/chromium/src/base/message_loop.cc:434 17 xul.dll base::MessagePumpForUI::DoRunLoop ipc/chromium/src/base/message_pump_win.cc:214 18 xul.dll base::MessagePumpWin::RunWithDispatcher ipc/chromium/src/base/message_pump_win.cc:53 19 xul.dll base::MessagePumpWin::Run ipc/chromium/src/base/message_pump_win.h:78 20 xul.dll MessageLoop::RunInternal ipc/chromium/src/base/message_loop.cc:208 21 xul.dll MessageLoop::RunHandler ipc/chromium/src/base/message_loop.cc:194 22 xul.dll MessageLoop::Run ipc/chromium/src/base/message_loop.cc:175 23 xul.dll XRE_InitChildProcess toolkit/xre/nsEmbedFunctions.cpp:481 24 xul.dll XRE_StringToChildProcessType toolkit/xre/nsEmbedFunctions.cpp:211 25 plugin-container.exe __tmainCRTStartup crtexe.c:552 26 ntdll.dll __RtlUserThreadStart 27 ntdll.dll WinSqmSetIfMaxDWORD 28 ntdll.dll _RtlUserThreadStart 29 plugin-container.exe pre_c_init crtexe.c:261 30 plugin-container.exe pre_c_init crtexe.c:261 31 @0xfffddfff