''[Locked as a duplicate of https://support.mozilla.org/questions/1219566. Please follow up there, thanks.]'' Whenever I open Thunderbird for the first time each day, the web page: https://www.bitcoinfyi.com/early-tech-investor-says-bitcoin-will-be-bigger-than-the-internet?utm_source=facebook opens automatically in my browser (in this case Firefox). If I start Firefox before starting Thunderbird, the web page does not open. I have tested this scenario extensively, so it's not Firefox - it's definitely Thunderbird. In fact, I went a whole day just using Firefox and not starting Thunderbird without seeing the bitcoin page. How do can I stop this from happening in Thunderbird? What tools are available that would alow me to troubleshoot it? I would very much appreciate your ideas. So far, I did searches within Thunderbird (i.e. I searched my e-mail messages) for "bitcoinfyi," "bitcoin," etc., but nothing can back in the result. I also searched about:config without any result. I ran several scans using SpyBot S&D, Malwarebytes, Microsoft Security Essentials, and my antivirus software (360 Total Security). None of these scanners returned any malware or spyware related to the bitcoin issue. It always displays the same page - an article from April 23rd, 2018. I submitted the URL to Virus Total (www.virustotal.com) for analysis and review - Virus Total reports the site as clean. I typed "early tech investor says bitcoin bigger than the internet" into a Google search and found links to the article associated with cnbc.com, twitter.com, coinnewstelegraph.com, truthinmeida.com, etc. in the result. These sites seem to be referencing the same article. I don't understand why or how this article has infected my Thunderbird software. I appreciate any help you can give. Thanks,