Product Firefox Release Channel release Version 53.0.2 Build ID 20170504105526 OS Windows 10 OS Version 10.0.15063 bp-5f3ce236-ff4e-4b84-a348-401eb1170512 Signature: shutdownhang | _PR_MD_WAIT_CV | _PR_WaitCondVar | mozilla::CondVar::Wait | nsEventQueue::GetEvent | nsThread::nsChainedEventQueue::GetEvent | nsThread::GetEvent | nsThread::ProcessNextEvent | NS_ProcessNextEvent | mozilla::net::nsHttpConnectionMgr::Shu... This is for Sumo's Related Bugs 1158189 REOPENED --- shutdownhang in mozilla::net::nsHttpConnectionMgr::Shutdown() IPSEng32.dll = Symantec Intrusion Detection Nvwgf2um.dll = NVIDIA Compatible D3D10 Driver = NVIDIA Corporation ------------------ A 'shutdownhang' is when Firefox is taking too long to close. Does this happen a lot? How long was Firefox running? [https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode Start Firefox in Safe Mode] {web link} by holding down the '''<Shift> ''(Mac=Options)''''' key, and then starting Firefox. A small dialog should appear. Click '''Start In Safe Mode''' (not Refresh). Is the problem still there?