With help from one of our members we solved the very complicated error far down in the webtechnology with domains and stuff. Million Thanks!
History: After an upgrade a domain certificate was not correctly installed which has been corrected. Some still have problems and we do not know why.
We asked our members who had problems accessing www.sbn.no to please send us a print screen*. It turned out we needed more. Finally one technical peson from DFØ made some kind of trace and the error was in this way documented, and could therefore be solved. It was a few levels down a setting in a doin at a domainregister where something was changed and now it works perfectly.
Even if all was OK according to experts and perfect set up. We still got messages, see the picture below from a few members who could not reach the www.sbn.no page. A trikky error.
This is how it can looked: 
*)A print screen of the full screen including the link to the page on the top an any additional information you may have.
Experts told us all is fine and we were therefore totally lost and needed all help we could get, to fix the problem. Thank you for the help we got!!
Eva-Maria