When processing the Security Updates this morning on 45 ESR and 50 Non ESR multiple PCs are hanging during install advising "The update could not be installed. Please make sure there are no other copies of Firefox running on your computer, and then restart Firefox to try again" and then Firefox will attempt to update. However it hangs during update and spins the working icon. These are on Windows 7 and Windows 10 PCs both. Same errors. On one PC I uninstalled Firefox. Then reinstalled the 45.3.0 ESR. It then updated successfully to 45.5.1 ESR. Is this a known issue with todays update? Update history shows several successful previous to this with no issues.