secure login to (Hungarian) vatera site

Hello opera users:

I frequently login to Hungarian bidding site www.vatera.hu
(https://www.vatera.hu/user/account/)
through secure login using opera web browser (11.51 linux version).

Every time when I try to login a "security issue" window pops up saying:

Under the "Warning" tab:

"The server's sertificate chain is incomplete, and the signer(s) are not registered.
Accept?"

Under the "Security" tab:

"(1) The certificate for "*.vatera.hu" is signed by the unknown Certificate Authority "Advanced e-Szigno CA3". It is not possible to verify that this is a valid certificate.
(2) The certificate for "Advanced e-Szigno CA3" is signed by the unknown Certificate Authority "Microsec e-Szigno Root CA". It is not possible to verify that this is a valid certificate.
(3) The certificate for "Microsec e-Szigno Root CA" is signed by the unknown Certificate Authority "Microsec e-Szigno Root CA". It is not possible to verify that this is a valid certificate."

At every login I check (turn on) "Remember my choice for this certificate" option and click the "Approve" button.

Sometimes I even have to click the "Approve" button several times after each other since new windows pop up.

But the next time when I try to login the security window(s) pop(s) up again and again. It is very annoying.

I have two questions related to this:

1. Why does not opera remember "my choice"?
I would except that after checking the corresponding check box, next time the security
window wouldn't pop up again.

2. Why opera can not accept the certificate(s)?
Firefox web-browser never has security problem with the site, no annoying pop ups are shown.


Thanks in advance,

suseuser04