This can be caused by a corrupt file, for derails on how to fix it see https://support.mozilla.com/kb/Toolbar+keeps+resetting

Thank you Tony, but I have done that twice and it doesn't fix the problem. I think I will probably go back to 3.6, as I don't much care for the new layout anyway and it doesn't support a couple of my add-ons either. Appreciate your help.

Did you delete the file localstore.rdf in the Firefox Profile Folder ? Help > Troubleshooting Information > Profile Directory: Open Containing Folder

Create a new profile as a test to check if your current profile is causing the problems.

See:

• Basic Troubleshooting: Make a new profile

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

Thank you for your suggestions, I appreciate it. I have reverted to 3.6 and all these problems have gone away. Over the years I have grown very tired of software "updates" which create new problems (and solve others which don't exist), and I no longer have the patience to sort out what the developers should have done in the first place. I guess I am becoming grumpy in my old age.

I have gone through the reset several times but to me the issue is that this file keeps getting corrupted. No sooner do I fix the problem when it comes back. I do not like the new default layout and want to change it but I am tired of redoing it every other day.

Files shouldn't get corrupted that often and that easily.

Did you check that Firefox closes properly and that there are no hanging processes left?

Do you have problems with other files in the Firefox Profile Folder?

Make sure that you do not use the same profile folder with different Firefox versions.

If you keep having problems with your current Firefox Profile Folder then create a new profile to see if that works better.

See:

• Basic Troubleshooting: Make a new profile

There may be extensions and plugins installed by default in a new profile, so check that in "Tools > Add-ons > Extensions & Plugins" in case there are still problems.

If that new profile works then you can transfer some files from the old profile to that new profile (be careful not to copy corrupted files)

See:

• http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox

myself was a FF user for last 12 yrs !! even i remember recommending ppl abt it...but FF 4 is a real PAIN IN THE APPROPRIATE PLACE....

it hogs memory...for simple functions (available by default in previous vers) ,now u have to install add-ons for them (like new tab button, FF4 either lets u have a new tab button OR the "+" button near opened tabs..but U CANT HAVE THEM BOTH SAME TIME!! WHAT THE.......

PC hangs/freezes almost everytime i ran FF 4 ..and for that i have lost valuable data..mind u, my machine config is not outdated. I have reverted back to previous vers FF 3.6...and am NOT UPDATING IT SOON....

ALL OF U FOLKS HAVIN PROBS WITH FF4 : easiest solution for all your probs -

1) get rid of FF4 and install the previous vers - http://www.mozilla.com/en-US/firefox/all-older.html after backing up - https://support.mozilla.com/en-US/kb/Backing+up+your+information

OR

2) get an alternative browser

yes folks, the above solution will at least give u peace of mind and a more peaceful good night sleep

If you have severe problems with Firefox in the current profile then it is best to create a new profile to see if that works better. I usually create a new profile for each major version update to get rid of remnants from the previous version. Most of them are prefs (prefs.js) that are no longer supported, but localstore.rdf with the toolbar customization can also be considered as a candidate for removal. That also allows me to check the content of other customization files (userChrome.css). I keep the old version available for testing and that can use the old profile. There are also a lot of extensions that cause problems and aren't working properly until they have been tested thoroughly and updated.