If I tag a post with a tag that is also the name of an existing category, the tag takes on the case of the category name.
For example, if I add the tags:
radio, adverts, music
I already have a category called Music, so the tags on my post become:
Why is there this link between category names and tags? As far as I'm concerned, tags and categories are two separate things, so I'd like to be able to use different case, even if the word happens to be the same.