Hi, Please check if this happens in [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [http://support.mozilla.com/en-US/kb/Uninstalling+add-ons Uninstalling Add-ons] [http://kb.mozillazine.org/Uninstalling_toolbars Uninstalling Toolbars]

Hi Vivek.Wilfred, thanks for answering so quickly. It seems that DoNotTrackPlus 1.4 has been the cause of my problems. This doesn't make any sense to me how this extension would be the cause. But I'm glad to have that problem solved. Thank you again for all of your help.

Such extensions maintain a permanent set of opt-out cookies that can't be removed.