I’m seeing the same thing. I’ve gone through the troubleshooting steps on the wp site. All is good. Checked .htaccess at web root and .htaccess at wp-content/cache. All match posts I’ve been finding.
I’ve also tried 0.7 to see if fixed. I’m running wp 2.6.1 on a ReadyNAS so web site is 1 directory down. All I get are 403 errors until I remove .htaccess in this root – then all is well.
No other plugins except autoupgrade and permalink redir.
Thanks.