hello jhart, does this popup also appear when you launch firefox in safe mode?

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

You may also check that you haven't set the home page to a page that try to download or install that toolbar.

• https://support.mozilla.org/kb/How+to+set+the+home+page

You can also check the download manger window and for problems with the sessionstore.js file.

• https://support.mozilla.org/kb/Downloads+window

You can try to delete the sessionstore.js file and possible sessionstore-##.js files with a number and sessionstore.bak in the Firefox Profile Folder.

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

Deleting sessionstore.js will cause App Tabs and Tab Groups and open and closed (undo) tabs to get lost, so you will have to create them again (make a note or bookmark them).

See also:

• http://kb.mozillazine.org/Session_Restore
• http://kb.mozillazine.org/sessionstore.js
• http://kb.mozillazine.org/Multiple_profile_files_created

Thanks a mil... I opened in safe mode and that solved the problem!

Hi... the issue is resolved... thanks for the suggestions!

running firefox in safemode is no permanent solution, just a step in diagnosing the issue - please have a look at your addons in firefox > addons > extensions and disable toolbars, extensions that you don't have installed intentionally or other ones that look suspicious... in case you find out what is triggering the pop-up please report back here, so that other users with a similar problem find a quick solution. thank you!

Excellente solution! In spanish go to Herramientas > Complementos > extensions and eliminate the abusive toolbar.

This worked for me:

How to disable extensions, Personas, and plugins

Disabling an add-on will turn it off without removing it:

   At the top of the Firefox window, click on the Firefox button (Tools menu in Windows XP), and then click Add-ons. The Add-ons Manager tab will open.
   In the Add-ons Manager tab, select the Extensions or Appearance or Plugins panel.
   Select the add-on you wish to disable.
   Click the Disable button.
   Click Restart now if it pops up. Your tabs will be saved and restored after the restart. 

To re-enable the add-on, find it in the list of Add-ons and click Enable, then restart Firefox.

Thank you... this worked for me too!