Dochoch, did you TRY what I suggested, ticking it on and off, and again, until you leave it unticked ?
Now, another precision : wordpress comes in two parts.
- the database, this is the contents you wrote, the options, the settings
- the blog files : the wordpress core (the root folder, the wp/admin and wp/includes folders), the customization files (the wp-content/themes wp-content/plugins folders), and lastly, the wp-content/uploads folder (I always avoided using that, precisely to keep things separated, but to each his own).
In this regard, on a standard blog you haven't started tweaking, you can SAFELY delete the contents of wp-admin and wp-includes, and also of the root folder (just make a backup of the .htaccess and wp-config file, or simply don't delete them two). And then reupload a fresh version from a wordpress.org copy.
(Ninja trick : ftp-upload everying in advance to a subfolder created for that occasion, and only after the upload is finished, delete the previously mentioned folders, and move everything to the root)
THAT is a clean reinstallation of wordpress.
And even if you do a clean wordpress reinstallation, all your posts, blog options, pages, uploads (do NOT delete the wp-content/uploads folder !) are safe and will be back at once. All that other stuff is stored in the database.
You can also try deactivating your plugins (link) and revert back to the default Twenty-thing template, to see if it fixes your problem.
Lastly - should have written it first -, you can simply reinstall wordpress from your admin's dashboard, I insist : this is SAFE, you won't lose anything, and it might perhaps fix your issue.