Google is giving me 404 not found for index page under errors for URLS in sitemaps?? Anyone ever heard of this?? Weird!
Found this: http://www.webmasterworld.com/google/3698804.htm I hope it is a bug in within webmaster tools.
there may be crawling error in the code because of broken or nested tables. check for HTML validation if there is any parsing error?
If it isn't a glitch, and the site is powered by Wordpress, check 404 redirects, or Easy redirects(?) I can't recall the exact name. (These are plugins to aid these kind of issues) Otherwise search for a redirect snippet and insert into .htaccess and see how it goes...
This happens sometimes due to network connection problems to your server, nothing much you can do about it except to resubmit the XML sitemap.