Did you check the Home page setting?

• How to set the home page - Firefox supports multiple home pages separated by '|' symbols

• Firefox has just updated tab shows each time you start Firefox

Checked the homepage setting and it is the same as always and doesn't load the plugin checker

Did you check for a problem with the preferences file prefs.js in the Firefox Profile Folder ?

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

checked that and found no problems there, I also tried changing my homepage and disabling loading my home page both of which worked fine but didn't stop the plugin checker tab from opening

I've had this issue for 2 days now. I can't find a way for it to stop loading the page https://www.mozilla.com/en-US/plugincheck/

From reading in here, there are a lot of other people that have just started to have this happen to them as well. I hope there is a way to turn it off.

It is possible that there is a problem with the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

Delete the files sessionstore.js and sessionstore.bak in the Firefox Profile Folder.

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder
• http://kb.mozillazine.org/Profile_folder_-_Firefox
• http://kb.mozillazine.org/sessionstore.js

If you see files sessionstore-##.js with a number in the left part of the name like sessionstore-1.js then delete those as well.
Deleting sessionstore.js will cause App Tabs and Tab Groups to get lost, so you will have to create them again (make a note).

See:

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

already tried deleting sessionstore.js without it making any difference

Here's what I did.

1) Went into about:config and looked at the plugins.update.notifyUser listing and saw that it was already on False. I changed it to True and then back to False. Also, the URL that is below it, I deleted the URL.

2) Went into Windows Program Manager and uninstalled the Viewpoint Media Player.

3) Went back into FireFox and selected Tools and Addons and disabled the MetaStream 3 Plugin.

Restarted the PC, and now it's back to normal where it open opens one tab with the about:blank.

That worked ! Thanks! After it was working I went back and reinstated the URL path to the plugin update page so that I can check for updates manually. I also ended up re-enabling the automatic update check without the problem coming back. It seems like Viewpoint Media Player and the MetaStream 3 pliugin were somehow the real problem.