Google reports a sudden increase in blocked URL's

[rachel2]

Getting Google message:

Google detected an significant increase in the number of URLs we were blocked from crawling due to authorization permission errors.

No change to generator, started appearing 1 week ago. Any Suggestions?

Also, validator reports "No Doctype" warning.

Thanks

[XML-Sitemaps Support]

Hello,

generator cannot block access to your pages, you need to check which pages exactly are reported as blocked and contact your site developer to fix this.