done by spider/incorrect url when the spider ran through your site. The spider probably grabbed the URL and cached the page, and if the page location was changed at any time, it will show that the object was moved and the cached page is no longer available. Not your fault at all. All about the spiders.
odd, check all your links and whatnot for any white spaces like: " http://"
Otherwise, the only reason that I could see that you would get that error is more due to rss feeds. If you have any on there, try removing them and running the spider again to see if that is your cause.