When you go to the Torrenting page to attempt log-in, where in the process does the error appear? (When you access the page or when you attempt to send the log-in?) It sounds from the error description you quoted that setting up a log-in to that site may involve the site server sending you a special client log-in certificate to be used thereafter. However, it appears that either Opera isn't accessing the old cert correctly, a correct cert no longer exists, or there's something wrong in the handshaking process with the server to negotiate the cert and perform verification. Have you tried setting up another account at the site (to obtain a new client cert)?