Sorry to hear. Have a check please just in case a report is there : https://support.mozilla.org/en-US/kb/firefox-crashes-asking-support Send if there is Please. Try this please : https://support.mozilla.org/en-US/kb/refresh-firefox-reset-add-ons-and-settings If that fails please uninstall Firefox after downloading a Full Version Installer for 56.0.1 from here : https://www.mozilla.org/en-US/firefox/all/ Your Flash is out of date so after please update to ver 27.0.0.170 https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> Now if can get that up and running Win 10 should be able to handle things. Though if you want to correct any errors in Win 10 can do this: Repair System Registry and Files (FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN) To run the SFC command use the Windows key + X keyboard shortcut to open the Power User menu and select Command Prompt (Admin). Type "SFC /SCANNOW" (without quotes or copy/paste) and press Enter. For more information on using SFC, please refer to the Microsoft KB: Use the System File Checker tool to repair missing or corrupted system files Run the Windows Deployment Image Servicing and Management (DISM) and System File Checker (SFC) tools as Administrator. The DISM and SFC tools scan the integrity of the Windows image and all protected system files replaces corrupted, damaged and incorrect versions. (FOR DOING Above & Below - WINDOWS All OTHER VERSIONS - Use Search To Find Command Prompt ** Enter CMD.exe to Find COMMAND PROMPT Then Right Click & RUN AS ADMIN) Windows 10 To run the DISM command use the Windows key + X keyboard shortcut to open the Power User menu, then select Command Prompt (Admin). Type "DISM /Online /Cleanup-Image /RestoreHealth" (without quotes or copy/paste) and press Enter. While running DISM you may notice the process will appear to pause at 20%. After a few minutes the operation will continue. If still have issues it maybe in your profile and we can help with that : https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles Please let us know if this solved your issue or if need further assistance.