Ninja
I did some test.
If i not use Sub category for my articles, and set all them to only one "root", the voice of menu show ALL the articles, and if i select one, the error not "pop up", but if the first articles is alway empy !!!, from the second it display well (also if navigation at bottom show up overlapping the text, but i think this is only a setting that can be changed).
So the problem seems to be the Sub category: if i use i have the error
P.S. i changed the name of the sub category just for testing and i did some test with and withou TAGS in the article with not good results.
I gave you superuser access