Since the latest update to wordpress, images are automatically made into hyperlinks, hilariously to themselves.
I can see how this would be useful if you were using thumbnails and linking to a big version, but 99% of the time, this just adds useless code and confuses visitors who click on the images by accident.
I also know that once you uncheck the box then it won't happen again, but amateur bloggers are now making posts everywhere with these annoying links in them. Plus, if you run a big blog, it's one more thing you have to explain to people who don't understand HTML to avoid.
Can we please make UNLINKED images the default in the next revision?
Just my two cents.