Specialities in digital signing on SEB internet bank website (Mac OS X and Windows)
Before anything else please update your ID-card software. This can be done from https://installer.id.ee/ website.
SEB - check that Preferences -> Functions -> Software used for digital signing is set to "ActiveX/Plugin" not "Java Applet"
NB! For some reason SEB internet bank requires you to confirm this change by digital signature. So if you had "Java Applet" , which doesnt work then you cant even confirm this change. The solution is to to make and confirm changes on some other (preferably Windows) computer.