WordPress theme reverts to default and all post/page data disappears

I am battling a rather strange gremlin with one particular website under development for a client (www.glasshousedesigns.com.au).

Using Genesis and their sample child theme as a template, I have built a custom child theme. The theme works perfectly and incorporates a number of plugins including:

– Simple Hooks
– WP eCommerce + Gold Cart
– WP Cycle
– Mail Press

There are no obvious plugin conflicts and the site operates as required.

However, at random intervals (usually overnight, but sometimes after so many hours of rebuilding) the entire WordPress installation reverts to the default ‘TwentyTen’ theme, all posts/page/product data disappears from the Dashboard and all plugins automatically deactivate.

I have checked MySQL and the database still seems to contain all data. Furthermore, the Genesis theme and custom child theme remain in the File Manager or accessible via FileZilla.

I have tried fresh installations of the entire WordPress site, have rebuilt each component from scratch and even hosted the domain with different host providers that I manage accounts with. I have run the ‘repair db’ function in MySQL but this has not fixed the problem.

I have installed and built hundreds of WordPress sites in recent years (including many Genesis based custom child theme sites), but never encountered this issue before.

I am also searching the Studiopress and WP eCommerce forums for a possible solution. I have encountered many forum posts where the theme reverts to the default (and the solution has been to save the preferred theme as the default) however, my problem seems widespread and also reverts all aspects of the database (posts/pages/products).

Any suggestions are most welcome 🙂