EDIT: It was the default menu (create automatically?) which was shown in the left sidebar.
I don’t know why. After I had deleted all items in the the default menu, the content in the left sidebar become empty.
EDIT2: Something strange happen.
– I Open Appearance/Menus. A menu “Menu 1” is shown with items to my pages. If I delete the menu items one by one, and then click “Create Menu” the published left sidebar gets empty. But the “Menu 1” structure exist in “Appearance/Menus”.
The Menu structure pane (without items) has a link “Delete Menu”, and when click this, same menu items are created again. And the published page shows the menu list in left sidebar.
EDI3: Problem solved! In Customizing/Layout/Primary Navigation/Navigation Location was set to left sidebar! I changed it to Below Header, and now everything is ok. Sorry for this trouble, but I very new on WordPress.