Which security software (firewall, anti-virus) do you have?

Do you have security software that may be running Firefox in a sandbox environment and restore some files and/or settings on reboot?

My security software is Norton Security Suite (2013), supplied by Comcast. I re-installed Firefox from my non-adm account although I did have to supply my administrator password. Same problem. Firefox always goes to the default Firefox opening page. When I go to my Administrator account I get the page I set (in Options) as my desired default (my.yahoo), even though I set it while logged in to my non-adm account. In other words, I installed Firefox and set the default opening webpage (my.yahoo) in my non-adm account. When I boot Firefox in my non-adm account, I get Firefox default page. When I boot it in my Adm account, I get my.yahoo. Norton Suite was originally installed in the Adm account and no changes were made when I created the non-adm account. I don't have this problem with other browsers.

You can check for problems with preferences.

Delete a possible user.js file and numbered prefs-##.js files and rename (or delete) the prefs.js file to reset all prefs to the default value.

• http://kb.mozillazine.org/Preferences_not_saved
• http://kb.mozillazine.org/Resetting_preferences