Google can produce bad Url references (href) on a cached page by injecting an incorrect BASE tag

A large client site is generating a lot of invalid page reference errors when the referrer was the Google page crawler engine (Googlebot). Google injects a BASE tag into the cached version of the page. In our case, because of a redirect to a language subfolder, this was wrong. If you used Google to find the site, but clicked on the cached version you could see that relative Urls were wrong.

Now the site has it's own base tag - set to the correct subfolder. Lets see if Google will leave our base tag alone next time the page is regenerated. Hopefully it doesn't overwrite the tag with a bad path as before.

PS: sorry I didn't manage to ungeek this issue at all!