Mac OS X, System Preference (SP) becomes locked after inserting ID-card to the reader
SP will be locked in Mac OS X after ID-card is inserted to the card reader, meaning that after this it is impossible to make changes to SP.
This situation can be solved by removing the ID-card from the reader and restarting your computer. Although when you insert your card next time the SP will be locked again.
This is a known Mac OS X error and affects all smart cards not just estonian ID-card's
This error has also been reported by Mac OS X users to the Apple forums and the discussion can be found here.