Does leaving out the hostname lead to Google making up URLs?

[schuon]

For a week now I have a massive amount of 404 notification in Google Webmaster Tools. They all follow the same pattern /MyPage/MyPage/ where only /MyPage/ would exists. I've examined the respective pages and the only time a link to /MyPage/ exists is within the breadcrumbs.
We don't have a URL with hostname in there, because it's easier to move from development machines to production. My question would be, has anybody used Microdata Breadcrumbs and seen Googlebot create weird URLs out of it?
Cheers,
schuon

[deadsea]

Relative links can end up causing more corner cases than most webmasters first imagine. In my experience, there is almost always some way to view a page with broken links, Googlebot doesn't just make up urls.

Sometimes it has to do with somebody adding an extra slash in the url: http://example.com// Check your site like that, do the links point where they should?

Sometimes it is navigation templates that are used in a subdirectory that breaks relative links.

I have tended to start my urls with a slash: href="/foo.html" rather than href="foo.html" so that it goes back to the server root. Many fewer problems without resorting to specifying the host name.

[matrix_jan]

1.check you website for 404s with Xenu
2.use Base Tag for relative linking

[schuon]

@deadsea: that's exactly what I do, all my URLs start with a / .
@jan: good idea, I'll have xenu run. So far I only used SEO Frog Spider, which seems to adhere to standards a little more than Xenu.