I've got a strange problem when I use pretty links %postname% and trigger a 404. When pretty links are off then the site displays the correct "No content" statement built into the theme files. But the moment I turn pretty links back on I get some strange extracts of the page code. Its seems that the page is being read from a few dozen lines of HTML in (so view source shows that <html.... etc is missing and it starts from somewhere in the body tag.
It isn't just one site that I have this on - all custom themes - and I don't know what I am doing wrong.
Anyone else had this? Any idea how I can solve it?
Thanks