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Those links appear to come from text on those pages. We've started picking up text that looks like URLs on HTML pages and seeing if they lead to new content. Sometimes those links are truncated and useless, but it's easy enough to try them and forget them if they lead nowhere, so we've started doing checking them to be sure. We primarily use these kinds of URLs for discovering new content.
I realize that this can lead to a somewhat cluttered crawl errors section in Webmaster Tools, so we're looking into ways of making that a bit clearer....
At any rate, you don't need to "fix" this problem (eg with a 301 redirect), if you're sure that the URL should really not exist.
A 301 redirect of a page that has never actually existed to a 404 page isn't a problem
they are using non-hyper-texted URLs to find new content and it sometimes causes 404 in WMT.