Reading the above, I can add pages to the menu just fine. But the different categories will not register in the menu. Like you can click on Paraguay, for example, and posts under Paraguay will not come up. Same for all other categories. But the "Learn Spanish" page in the menu does open. Home also works, but nothing else.
I can add categories to the menu but the posts will not go there. The menu did work fine until I tried to change it so I had "Countries" at the top and the four countries as sub-menus. It looked good but did not work. When that didn't work I changed it back but it was messed up then. After reading the above I just disabled all plug-ins as mentioned above (no exceptions), and they are still disabled but it didn't change anything else. Categories still don't work. I did try changing the theme as suggested and when I did that, nothing but "Learn Spanish" and "Home" showed in the title bar. The other menu headings were no longer in the title bar.