Can you find any indication that Firefox is crashing? Often when Firefox crashes, it records information about what was happening at that moment. You can submit that data to Mozilla and share it with forum volunteers to see whether it points to the solution. Please check the support article "Firefox Crashes" (especially the last section) for steps to find any available crash report IDs, and then post some of the recent ones here.

More likely, some process is telling Firefox to exit. That would make sense since your previous session restores with only one active window (the last one to close). But what and why?! Do you have any kind of clean-up utility that might want to modify Firefox settings files that could be closing Firefox?

As a temporary measure until the mystery is solved, to make sure you can recover more of your previous session, you can increase some hidden parameters:

(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 search box above the list, type or paste sess and pause while the list is filtered

(3) Double-click the following preferences to edit their value as desired:

(A) browser.sessionstore.max_windows_undo - this is why you currently only get 3 closed windows back

(B) browser.sessionstore.max_tabs_undo - if 10 closed tabs per window is too few

I doubt I have any clean-up utility, unless it is automatic and I activated it without knowing it. I made no changes prior to these recent exits (or crashes). I've had 3 or 4 in the past 7-10 days. FF worked just fine for the first two years I used it, then, six months ago, I've had problem after problem. I've tried to read up on this and it looks like I started having problems about the time FF went to Australis.

I don't get any kind of report or alert that FF has crashed or even closed. It is just closed when I get on my computer. Sometimes plug-in.exe states that it had to close, sometimes not.

Hi ikonoklast61, the Australis UI was introduced with Firefox 29, about 20 weeks ago.

Perhaps there is an incompatibility with one of your extension? You could try restarting Firefox in its Safe Mode before going to bed to see whether that has any effect. That's a standard diagnostic tool to deactivate extensions and some advanced features of Firefox. More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using either:

• "3-bar" menu button > "?" button > Restart with Add-ons Disabled
• Help menu > Restart with Add-ons Disabled

Not all add-ons are disabled: Flash and other plugins still run

After Firefox shuts down, a small dialog should appear. Click "Start in Safe Mode" (not Reset).

Any difference in the morning?

every time I have a problem with FF recently, someone suggests this. I try it and learn nothing.

Did you even try to look for Crash Reports (so we can try to help you) as mentioned in this section of this support article? https://support.mozilla.org/en-US/kb/firefox-crashes-troubleshoot-prevent-and-get-help#w_get-help-fixing-this-crash

If you don't want help, but rather posted here to express your displeasure with Firefox, please provide feedback directly to Mozilla, here: https://input.mozilla.org/en-US/feedback

Overall, you get as much help out of the support process as the effort you put in!

I looked at the crash article you mentioned earlier and didn't see anything that would help, or that I could figure out would help. The last Time I had a problem, I went through the forum and tried everything I could find with no results. I asked for help and did everything I was told with no results. The guy who was helping me told he had to call in professional help and I never heard back from him. maybe I know less about what to do than you imagine. I DID NOTHING DIFFERENT BEFORE THIS PROBLEM STARTED, which is why I'm dubious that ball of a sudden the few add-ons I have are acting up. I said I don't know anything about utilities causing FF to close. I just again looked at the crash report you included: the last crash report was 8-20, over 2 weeks before the problem I am writing about. I also mentioned that I'm not getting a crash alert when this happens. What am I not doing that I should be?

As far as I can tell from your description, Firefox isn't crashing, it's closing one window at a time until they are all closed, which is characteristic of an external command to shut down the application.

If you don't like my suggested experiment of leaving Firefox in its Safe Mode at the time you leave your computer for the night perhaps you can think of a better way to rule out extensions as possibly triggering this shutdown. That's the only one that came to mind for me (other than manually disabling all of them, which is more work).

As long as you are scouring your computer for potential culprits, check the Windows Task Scheduler to see whether there is anything scheduled to run at night:

• Windows XP: Start button > [All] Programs > Accessories> System Tools > Scheduled Tasks

• Windows Vista/7: Start button > Control Panel > System and Security > Administrative Tools > Task Scheduler

I can try leaving it running at night in safe mode, but AGAIN, I've made no recent alterations such as adding add-ons so why would that be the problem all of a sudden? What am I supposed to be looking at in the task manager? Of course I have open applications all the time. Again, nothing new or unusual as far as I know.

Hi ikonoklast61, sorry, not the Task Manager but the Task Scheduler. Please see the path from the Start menu in my earlier post.

What is the file size of the sessionstore.js file in the Firefox profile folder?

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

• Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder)

Are there plugins active in tabs when this happens?

You can check for issues caused by plugins and set all plugins to "Ask to Activate" on the "Firefox/Tools > Add-ons > Plugins" page (plugins are not affected by Firefox Safe Mode)

jscher2000: sorry, my mistake. I checked it and saw several updates that run at various times during the day, such as google update, adobe update, etc. I've disabled all these for the time being. The problem is, FF doesn't close every day -- I think it's been 3 times in 8 or 10 days maybe.

cor-el: file size is 3 KB; the "always activated" plug-ins, which I've set to "always ask" were for Microsoft DRM, QQ, Shockwave, silverlight, nitro PDF, Windows Media Player and Microsoft presentation. And again, none of these are new.

Your System Details shows;

Installed Plug-ins

Shockwave Flash 14.0 r0

Adobe Shockwave for Director Netscape plug-in, version 12.1.3.153 Adobe Shockwave for Director Netscape plug-in, version 12.1.2.152

Having more than one version of a program may cause issues.

Remove Adobe Shockwave for Director Netscape plug-in, version 12.1.2.152

Update your Shockwave Flash v15.0.0.152 http://get.adobe.com/shockwave/

It could be the work of one of your add-ons, or even add / mal-ware. Open your Add-ons Manager <Control><Shift> A and make sure you know what each one is and what it does.

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

Also, check the programs that are on your computer

Windows: Start > Control Panel > Uninstall Programs. Mac: Open the "Applications" folder. Linux: Check your user manual.

Go thru the list. If you find something that you don't know what it is, use a web search.

Troubleshoot Firefox Issues Caused By Malware {web link}

Possible Mal-Ware Scan For Macs {web link}

thanks for the suggestions. I deleted the duplicate and checked the add-ons. I don't see any extra toolbars and I use malware bytes daily. I shouldn't have any malware.

It's quite possible some of my add-ons have unforeseen consequences -- but if so, they didn't start showing up until a month after I installed them.

If you still had the problem in safe mode (add-ons disabled), then it could be one of your system programs.

When you go to bed tonight;

Start your Computer in safe mode. Then start Firefox. Leave the computer running, but disconnect all internet access. Unplug you modem, for example. And turn off WiFi.

Starting The Computer In Safe Mode;

If running, turn your computer off. Remove any disks and thumb drives that are in your hard drives or ports. Now start your computer but also;

Windows; Press the <F8> key repeatedly. Mac: Hold down the Shift key. Linux; Using the command line, Linux/Unix computers can be booted into various run levels that determine which resources are loaded. For example, "runlevel 1" is typically the equivalent to Windows and Mac safe modes.

• Source; Safe Mode; Free Online Encyclopedia

When the Boot menu is displayed, release the key you were pressing. You must now choose what mode to use. The most used are;

• Safe Mode; The computer runs with only a minimum set of programs.
• Safe Mode With Networking; Same as above, but with internet access.

I went back to 28 and have had NO problems.