Separate Security Issue: Update your Flash Player or remove it using these links; http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html Uninstall Flash Player | Windows http://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html Uninstall Flash Player | Mac

Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version: Version 30.0.0.113

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

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> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

You may have corrupt sessionstore [v56] sessionstore.jsonlz4 file(s). Delete all sessionstore* files and the sessionstore-backups folder.

Type about:support<enter> in the address bar.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox.

Don't delete the files if you need to rescue any data from them, just move them out of the profile folder to some location where Firefox doesn't look for them. You can try to read out their contents using this tool: https://www.jeffersonscher.com/res/scrounger.html

Use one of these to close Firefox if you are currently doing that by clicking the close X on the Firefox title bar to make sure Firefox closes properly.

• "3-bar" menu button -> Exit (Power button)
• Windows: File -> Exit
• Mac: Firefox -> Quit Firefox
• Linux: File -> Quit

If you use "Clear history when Firefox closes" then try to disable this feature.

• Options/Preferences -> Privacy & Security
  Firefox will: "Use custom settings for history":
  [X] "Clear history when Firefox closes" -> Settings

Hi RandyHintz, you may have inferred this from the above replies, but just in case:

The #1 reason this would happen is if Firefox did not shut down normally. In that case, Firefox will perform a crash recovery, resuming your previous session automatically.

(Sometimes the automatic crash recovery doesn't work and Firefox instead shows a screen asking if you want to start a new session or try restoring some or all of your previous session windows and tabs.)

A couple other reasons Firefox might restore your earlier session:

• A "cleaning" program removed the latest session history file, so Firefox assumed that it crashed and used an older one. If you are getting pages from a much earlier session instead of the latest one, this could be the cause.

• There is a user.js file with an instruction to restore your previous session. You can remove or edit this file; there's a section on that issue in this article: How to fix preferences that won't save.

Thank you all for the replies! I have found and fixed my issue, and I believe all 3 replies led me to the final solution.

I found my user.js file and opened it, the last line was: user_pref("browser.sessionstore.resume_session_once", true); While Firefox was still open, I edited this file in Notepad++ and removed that line. I saved and closed the file and closed FF.

Next time, I opened FF and voila! A single blank tab! I opened a few tabs, closed FF and tried again, success again!

Any idea what may have put that line in the file to begin with?

Thanks again for the help!!

What else is in the user.js file?

The user.js file will only be present if you or other software has created this file and normally won't be present.

You can check its content with a text editor (right-click: "Open with"; do not double-click). The user.js file is read each time Firefox is started and initializes preferences to the value specified in this file, so preferences set via user.js can only be changed temporarily for the current session.

You can delete the user.js file if you didn't create this file yourself.

Thanks for the reply cor-el!

Here are the rest of the contents which are still in user.js:

user_pref("extensions.blocklist.enabled",false); user_pref("extensions.blocklist.interval",31536000); user_pref("extensions.blocklist.url",""); user_pref("extensions.blocklist.itemURL",""); user_pref("extensions.blocklist.detailsURL",""); user_pref("security.mixed_content.block_active_content",false); user_pref("security.mixed_content.block_display_content",false); user_pref("app.update.staging.enabled",true); user_pref("browser.safebrowsing.appRepURL",""); user_pref("app.update.silent",true); user_pref("browser.safebrowsing.updateURL",""); user_pref("browser.safebrowsing.reportURL",""); user_pref("browser.safebrowsing.reportMalwareURL",""); user_pref("browser.safebrowsing.reportMalwareErrorURL",""); user_pref("browser.safebrowsing.malware.reportURL",""); user_pref("services.sync.prefs.sync.browser.safebrowsing.enabled",false); user_pref("services.sync.prefs.sync.browser.safebrowsing.malware.enabled",false);

Hmmm, when I went to my Add-ons manager to see what I have, I found one I do not recognize: "Web Security 1.0.0" https://addons.mozilla.org/en-US/firefox/addon/web-security/reviews/ I am going to remove that. If I remove user.js and other approved Add-Ons (like uBlock Origin) want to write to this file, then they will just do so, right?

uBlock Origin doesn't create or use a user.js file.

The user.js file contents appear directed toward disabling malware and phishing protections in Firefox. Legitimate extensions would not do that. You may need to go through about:config and righ-click > reset those preferences to regain protection.

Thank you the-edmeister! Thank you jscher2000! Both very useful information :)

Based upon what I have gathered from all the useful information in this thread, I believe the unrecognized "Web Security 1.0.0" Add-On put all of these lines into the user.js, and it appears to be aimed at weakening the browser's security! I am suddenly very glad that it (or something else) added the line user_pref("browser.sessionstore.resume_session_once", true), because that was the one that started this thread, but was simply the tip of a huge security iceberg!

Thanks to all! I am going to report that add-on for abuse and link to this thread.

Hi RandyHintz, extensions compatible with Firefox 57+ cannot directly modify user.js or other files other than their own extension storage, so there probably is another piece of software in the mix...

Hmmm, thanks jscher2000 - I will keep an eye on my folder and see if the file reappears.

Maybe that software that created user.js added that extension as well.

You can also compare user.js and prefs.js and remove matching lines from prefs.js with Firefox closed to cleanup changes made by user.js.

Thanks cor-el! I did check my prefs.js and found many of the same lines. I also had what appeared to be backups named prefs-1.js and prefs-2.js, is this normal? prefs-2.js was dated only about a week ago, but prefs-1.js was dated Dec 2017.

While FF was closed, I deleted the lines from above in prefs.js, and they are not re-appearing. Thanks for the suggestion to check there!