David Green, Thank you for your question, however we were unable to reproduce this in Firefox. Please update to the latest version of Firefox and if this does not help, please consider a new thread to grab the attention one more time.

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

See "Creating a profile":

• https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles
• http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues

If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems.

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

Thanks cor-el, I didn't know that the profile could be managed. The new profile appears to have corrected the problem. And to be safe, I have elected to rebuild rather than copy the profile contents.