Privacy Settings Reset

I have the plugin successfully installed however for several months now the privacy settings on one particular blog keep resetting from "registered users only blog" to "allow visitors but block search engines'. I have the default settings for the plugin set to allow override. However, all of the other blogs in my WPMU install are public...could this be why this one blog keeps getting reset?

Has anyone else had this issue?

I also have the following plugins installed and active - could they be causing a confilct?
MM Forms
SI-Captcha
Sociable
All-In-One SEO
Dagon Design Sitemap
Popularity Contest
Simple Forum
Tweet-MeMe
WP-PageNavi

Please advise.