1Check System Time: Ensure your computer's date, time, and time zone are correct, as incorrect settings are the most common cause of certificate errors.
  2 Verify Site Status: Try opening PCH.com in another browser (like Chrome). If the error persists there, the issue is likely on their end.
   3Disable Antivirus HTTPS Scanning: Temporarily turn off the "SSL/HTTPS scanning" feature in your antivirus software, as this often triggers Firefox's security warnings.
   4Trust Enterprise Roots: Type about:config in the Firefox address bar, search for security.enterprise_roots.enabled, and set it to true. This forces Firefox to trust your system's certificates.
  5 Clear Certificate Cache: Go to Firefox Settings > Privacy & Security > Certificates > "Manage Data" and click "Clear OCSP cache," then restart the browser.

AI gived me this answer Here is a concise but detailed troubleshooting guide (about 5-6 steps) you can provide to the user: 1Check System Time: Ensure your computer's date, time, and time zone are correct, as incorrect settings are the most common cause of certificate errors. 2 Verify Site Status: Try opening PCH.com in another browser (like Chrome). If the error persists there, the issue is likely on their end. 3Disable Antivirus HTTPS Scanning: Temporarily turn off the "SSL/HTTPS scanning" feature in your antivirus software, as this often triggers Firefox's security warnings. 4Trust Enterprise Roots: Type about:config in the Firefox address bar, search for security.enterprise_roots.enabled, and set it to true. This forces Firefox to trust your system's certificates. 5 Clear Certificate Cache: Go to Firefox Settings > Privacy & Security > Certificates > "Manage Data" and click "Clear OCSP cache," then restart the browser. sorry if this answer not help you