Extrange behavior with Google webmaster tool.

Hi there.

After install and configure the plugin, I sent the Sitemap to Google Webmaster. At first time Google say to me that there is error on sitemap

When I click on error, this happen:

http://screencast.com/t/WGQI6MjjxJU

Opening any of these link, you can see the famous 404 error detected. You can see an 404 error detected by Google.

http://screencast.com/t/82DgT7XZ6SV

But when I click on “Check Sitemap”. Google say that all is correct…

http://screencast.com/t/kvymaEMKIs

Can someone explain this?

Greetings