Q: My Firefox web browser has trouble connecting to secure websites such as Amazon and Netflix. I get the error message "SEC_ERROR_UNKNOWN_ISSUER," and a pop-up box claims that these websites aren't secure, or that I need new website certificates. I've reinstalled Firefox several times, but that hasn't solved the problem. What can I do?
Gene Schwope, Woodbury
A: The problem may be caused by a conflict between Firefox and your security software, or by malicious software on your PC.
Software conflict: Secure websites, such as those that handle financial transactions, provide Firefox with digital "certificates," issued by a third party, that guarantee the sites are legitimate. (See my previous column on website certificates at tinyurl.com/hl5hd9p).
But some PC antivirus software, including Avast, Bitdefender, BullGuard, ESET and Kaspersky, can interfere with Firefox receiving a website's certificate, triggering the error message you received. If you use one of these programs, change its settings (see tinyurl.com/zbgeruv).
Malware: Odd PC behavior can occur if your computer picks up malicious software from a website or e-mail. Run the free Malwarebytes security program (see tinyurl.com/jsdacdk).
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