Standard versions an installs of Firefox do not use multiple instances of Firefox although you may also see one or more pluginscontainer instances.

There is an option to choose whether or not to open tabs and windows from last time are you opting to use that ?

• Startup, home page, tabs, and download settings

Or is this the screen saying "... this is embarrassing" as Firefox tries to recover from a crash

• Restore previous session - Configure when Firefox shows your most recent tabs and windows_after-a-crash

It sounds rather as if you may have malware. You have file user.js in your profile that is something that is not there by default and indicates you or some software added that.

• http://kb.mozillazine.org/User.js_file
• Profiles - Where Firefox stores your bookmarks, passwords and other user data_how-do-i-find-my-profile

I may help to know what is in that file and it will only be a short text file so please find your profile from the troubleshooting page while Firefox is open and paste the file contents of user.js in to your initial reply.

Next please scan with all the tools listed in

• Troubleshoot Firefox issues caused by malware

Please then post back again to say what you did and what you found ? You may also find this thread of interest

• How to import Norton Identity Safe Vault into FF Password Manager /questions/1097768

You can check if you have a user.js file in the Firefox profile folder that sets the browser.sessionstore.resume_session_once pref to true.

• http://kb.mozillazine.org/browser.sessionstore.resume_session_once
• http://kb.mozillazine.org/Preferences_not_saved

You can use this button to go to the current Firefox profile folder:

• Help > Troubleshooting Information > Profile Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Windows hides some file extensions by default. Among them .html and .ini and .js and .txt and you may only see a file name without file extension. You can check the file extension (type) in the properties of the file in Windows Explorer via the right-click context menu.

So i checked my user.js file and this is what is in it user_pref("network.http.max-persistent-connections-per-server", 4); user_pref("nglayout.initialpaint.delay", 600); user_pref("content.notify.interval", 600000); user_pref("content.max.tokenizing.time", 1800000); user_pref("content.switch.threshold", 600000); user_pref("browser.sessionstore.resume_session_once", true); user_pref("browser.sessionstore.resume_session_once", true); user_pref("browser.sessionstore.resume_session_once", true); user_pref("browser.sessionstore.resume_session_once", true);

so it looks like the resume sessions are set correctly. Also i am currently running a malware check and nothing has come up yet. I do run Norton and have ran multiple scans with nothing found either.

So after the scan completed it found 10 malware pieces, i removed them and problem solved for now. Thank you

Thanks for posting back, and I am glad the problem is solved.

It does sometimes require multiple scanning tools, and the latest versions of them to find all malware.

Did you find and look at the contents of the file user.js if you delete that or change its name to something such as user.js.old that will prevent it affecting Firefox. It is possible one of the scans already flagged that as malware and you removed it,