hello, you should never ever need to manually install a certificate manually for a big commercial site like amazon, paypal or your bank in order to protect your data and sensitive information! something particular must be out of order on the system. first please make sure that the date, time & timezone are set correctly on your system. if this doesn't solve the issue (or it is already set properly), a possible solution depends on different factors: what is the '''error code''' shown under ''technical details'' on the error page?