After upgrading from 2.1 to 2.7, everything seemed fine, and i even decided to start using PHP5 to get Extended Live Archives working. The upgrade went well with no errors, and i could import all tags from UTW. The transition to a UTF8 database went well too.
Today i noticed that even tough all is fine in the Admin section (the category and all post are there, i can edit them etc), i couldn't get the posts in one category in the blog to show up. The category archives show, but when clicking on the posts' links i will get to the homepage.
Some poking around revealed this: for that one category, the posts will not show up, but the URL will be in the browser's address bar and links (like the read more link in the homepage) will think i am in the post's page.
The category is called "ensinamentos", and i can get the posts to display if i try mydomain/e/postname. If i substitute the letter "e" in the address by anything i will get to the post. If i substitute the letter "e" by "en" i will get a 404 (correctly). If i then substitute the letter "e" by "ens" i will get to the homepage.
For all other categories, if i try mydomain/anything-at-all/postname, i will get to the posts!!!
My htaccess is standart except for some 301 redirects (for old page management). I can post it here if needed, as well as the blog address for testing.
I will be gratefull for any help on this.