hi I have several different 2.5.1 WordPress Blogs that are having the same issue. They each use themes we found at themes.wordpress.org. What's happening is that if I select month and name permalinks instead of the default type, some of the pages on the site update and work fine at the new URLs and other pages generate CGI errors. They're all in one category, there isn't anything special about the pages that I can tell, but they don't work. I've read through the forums and Docs and haven't found anything there yet that helps. I activated Mark Jaquith's Disable Canonical URL Redirection Plugin to see if that fixed the problem but it made no difference.
The specified CGI application misbehaved by not returning a complete set of HTTP headers.
The main site I'm concerned about is http://www.hotelvegasdeals.com/
For example, when I have permalinks set to month and name, the Cool in Vegas link in the header generates the above CGI error, but the link to Diamonds in the Desert works fine.
I'm not sure if maybe the site index needs to be forced updated or something to make all the permalinks work?