@pierreparis Something - could be an external program, extension or even a setting - is deleting your login cookies. Does it happen every time you restart opera, or only when you restart the computer? (If it's when you restart the computer then it's an external program; if it happens when you restart Opera it is n extension or setting.)
@doedau54 I don't have enough on my speed dial to have scroll bars.. This page has arrows, on the other hand, Bookmarks or History or Personal News don't. So it seems to be only on internal pages.