Does that happen when you start Firefox?

Check the home page setting.

• https://support.mozilla.com/kb/How+to+set+the+home+page - Firefox supports multiple home pages separated by '|' symbols

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

Delete the sessionstore.js [2] file and possible sessionstore-##.js [3] 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:

• [1] http://kb.mozillazine.org/Session_Restore
• [2] http://kb.mozillazine.org/sessionstore.js
• [3] http://kb.mozillazine.org/Multiple_profile_files_created

The problem does not occur when starting Firefox. It occurs only after Firefox has been open/running for a period of time. I found only one occurrence of "sessionstore". I deleted sessionstore.js. I will let you know if this solves the issue. Thank you.

Problem still persists. Any other suggestions? Thank you.

I have added a screen print of window message. Thank you.

Problem appears to be related to using speed dial add-on for FF. Certain links saved in speed dial will repeatedly ask you to save files/programs.