This can be a problem with the files sessionstore.js and sessionstore.bak in the Profile Folder

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

• Help > Troubleshooting Information > Profile Directory: Open Containing Folder

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.

You will have to redo App Tabs and Tab Groups after deleting sessionstore.js.

See:

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

Deleting sessionstore.js and sessionstore.bak did not solve the problem. I also downloaded firefox 4 again but this did not help. The problem only occurs on my desktop, not on my portable.

Which does open if you start Firefox?

Are you using the default about:home Home page?

You can also try to reset all the preferences:

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

I'll try reseting the preferences tomorrow. A blank page is present on start up despite selecting home page in preferences. My home page is "my.yahoo.com" but the default home page also does not open on startup when selected. Clicking the home symbol does open the selected home page however. Thanks, Gordon

Removing the pref files and reopening Firefox did not correct the problem. I also noticed that the back button does not work. Gordon

This can be a problem with the file places.sqlite that stores the bookmarks and the history.

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

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

Cor-el The problem seems to be solved. Creating a new profile corrected the problem; however when I added the contents of the default profile back to the new profile the problem recurred. I then restarted Firefox in the safe mode to disable any add on etc. This also corrected the problem. I then enabled each add on one at a time until the problem recurred. The culprit was the Yahoo Toolbar! Without out this add on so far all is well. Thanks for your help. Gordon