Error when viewing orders

I get this error whenever trying to visit the Orders of Marketpress, before we had any, and now that we do.

This is the page I get:

This webpage is not available
The webpage at http://waldorfessentials.com/wp-admin/edit.php?post_type=product&page=marketpress-orders might be temporarily down or it may have moved permanently to a new web address.
Error 330 (net::ERR_CONTENT_DECODING_FAILED): Unknown error.