Firefox will ignore your startup setting and automatically resume your last session if it thinks it crashed. You can stop Firefox from doing this and instead present you a screen with the option to resume. If you see that screen after making the following change, then this is the problem. If you don't see the screen, it must be something else...

To prevent Firefox from automatically resuming your last session after a crash, you can change a setting as follows.

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the filter box, type or paste resume and pause while the list is filtered

(3) Double-click browser.sessionstore.max_resumed_crashes and set the value to 0. You're done in about:config.

After future crashes, when you restart Firefox, it should present you with a list of the windows and tabs you had open during your previous session so you can choose which, if any, to restore.

If you do not keep changes after a restart then see:

• http://kb.mozillazine.org/Preferences_not_saved

You can also 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

I also have this issue and have had since updating to Firefox 18.something. I have tried all the suggestions for changing things in the config, as well as creating a new pref.js file. I am running Windows 7 Pro. and Firefox 20.0.1 My Father have Windows Vista/Firefox 20.0.1 and my Grandfather has Windows XP/Firefox 20.0.1 and they have the same issue as well so it MUST be a Firefox issue.

Create a new profile as a test to check if your current profile is causing the problems.

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer some files from an existing profile to the new profile, but be careful not to copy corrupted files.

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Do a clean reinstall and delete the Firefox program folder before reinstalling a fresh copy of Firefox.

Download a fresh Firefox copy and save the file to the desktop.

• Firefox 20.0.x: http://www.mozilla.org/en-US/firefox/all.html

Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.

• Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.

Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.

• It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
• http://kb.mozillazine.org/Uninstalling_Firefox

Your bookmarks and other profile data are stored in the Firefox profile folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.

• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/Profile_backup

• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall

I set up a new profile as directed in the instructions and copied pertinent files and folders. And now it Firefox opens to the page I set in options!

All was well after creating new profile and copying needed files to it....until I tried to send an email with attachment......cannot attach a file or picture!!!! Any ideas to solve this???

Hi boats53, which mail site are you using (e.g., Outlook/Hotmail, Yahoo!, Gmail)? Is there a particular error message when you try to attach a file, or you click and nothing happens?

Using Yahoo mail. Get error at bottom where it shows the attachment loading, in red letters saying that it can't be done. I did a "switch" (whatever that is) that was an option and I did get an attachment to go through. Odd I never had a problem with the old profile and still don't if I switch back to it!