My "guess" (sorry, it's the best I have) is that the URL was not able to be resolved via the SEO addon and that you do not have a 404 page set.
Again, only a guess. What happens if you type in a truly garbage url like www.mydomain.com/foobar?
My "guess" (sorry, it's the best I have) is that the URL was not able to be resolved via the SEO addon and that you do not have a 404 page set.
Again, only a guess. What happens if you type in a truly garbage url like www.mydomain.com/foobar?