Brain drain

I don't know what's wrong with me. Often, when I'm typing something, I'll use the wrong word for something. I'm not talking a simple typo here, but the actual substitution of a word with a similarly spelt one, which is wholly different in meaning, often leading to some unintentional humour. I wrote a recent post here about Internet Explorer. Notice anything wrong with the post title? Yeah, that's right, it's called "Internet Exploder". I spotted it a couple of minutes ago. I thought at first I was being sarcastic, and referring to this annoying software's behaviour on my laptop. However, I realised it was another example of my new-found affliction. I discovered another one recently on my Flickr pages. A pic which should have been entitled something like 'Plaque in Llandeilo', had actually been named 'Plague in Llandeilo'. Not quite the same thing, is it?

Isn't there some disease or disorder that causes people to do this?