[plugin: WordPress SEO] permalinks keep resetting themselves

When this site was a fresh install I reset the permalinks to custom: /%category%/%postname%/. I installed this plugin and went on with other changes. A few months later I realized that the permalinks had reset to the default. Last week I changed them back. Today I see that they have returned to the default again. While it may not be this plugin, I used to use All in One SEO and never had this problem.

The theme is a child theme using the Howling Dog framework. The url is http://blueplanetlaw.com