Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Appearance
• do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

Nothing worked until I turned off hardware acceleration. Then all the tabs that wouldn't load disappeared! Marty

I'm trying to understand the original problem: you restored tabs from a previous session, but they loaded as blank, e.g., new tab? Users report this several times a year, but I don't know what causes the problem. It's probably some kind of corruption that crept into the session history file.

To maximize the potential for recovering the missing tabs, let's back up a few files and see whether any might have them. Here's how:

You can open your current Firefox settings (AKA Firefox profile) folder using either

• "3-bar" menu button > "?" button > Troubleshooting Information
• (menu bar) Help > Troubleshooting Information
• type or paste about:support in the address bar and press Enter

In the first table on the page, click the "Open Folder" button.

In your profile folder, scroll down and double-click into the sessionstore-backups folder. Save all files here to a safe location, such as your Documents folder. If not too much time has passed -- not too many restarts -- we may be able to use them to recover your lost tabs.

What files did you find?

The kinds of files you may find among your sessionstore files are:

• recovery.js: the windows and tabs in your currently live Firefox session (or, if Firefox crashed at the last shutdown and is still closed, your last session)
• recovery.bak: a backup copy of recovery.js
• previous.js: the windows and tabs in your last Firefox session
• upgrade.js-build_id: the windows and tabs in the Firefox session that was live at the time of one or more recent updates

Could you take a look at what you have and the date/time of the various files to see whether you think any of them would have the missing tabs?

Note: By default, Windows hides the .js extension. To ensure that you are looking at the files I mentioned, you may want to turn off that feature. This article has the steps: http://windows.microsoft.com/en-us/windows/show-hide-file-name-extensions

The sessionstore-backups folder had 3 entries - recovery.js, recovery.bak, and previous.js. saved to a safe place. All dated for the current date and time. Now what do I do? Sorry, but I have a difficult time with these .js files and how I handle them. Every few months all my tabs just disappear and I have never been able to restore them. This time was different as the tabs were showing but the all were blank. Thanks, Marty

There would normally be upgrade.js files in the sessionstore-backups if you have updated Firefox when using this profile. If these upgrade files aren't there then this would suggest that a new profile got created, either via a refresh or because of a problem with the profiles.ini file that registers profiles.

You can check in Windows Explorer with Firefox closed if there is a previous version of the sessionstore.js file available.

• right-click: Properties -> Previous Versions
• http://windows.microsoft.com/en-US/windows7/Previous-versions-of-files-frequently-asked-questions

Do you have an "Old Firefox Data" folder on the desktop as the result of using the refresh feature in Firefox?

You can check if you have orphaned profiles that aren't registered in profiles.ini and that do not show in the Firefox Profile Manager. You can check that by opening the current profile folder and go up one level.

• http://kb.mozillazine.org/profiles.ini_file