Secure connection: fatal error (1066)

Unable to verify the website's identity (OCSP error)

This normally means that the website tried to do OCSP stapling, and got it incorrect. This is a server setup issue, where the server gets a validity stamp (OCSP) for the certificate, and sends this stamp with the certificate. If the validity has expired, Opera 12 will show this error. Some servers might get OCSP responses valid for 3 days, and replace it every 5 days, so 2 out of 5 days, the setup will be incorrect, and Opera will refuse the insecure connection.

If you find this a problem, you can disable this check in the settings:

opera:config?ocsp#SecurityPrefs|OCSPValidateCertificates

Note that by doing so, you lose out on one of the security checks employed in Presto.