Please follow this article for Product Validation, but that would be the last thing you need to do since you can not validate an old XTheme and Cornerstone.
Your girl friend might have a latest WordPress, and outdated XTheme on latest WP is incompatible.
You need to manually update your X THEME and Cornerstone and the Extensions/plugins that is bundle with Xtheme first, you can follow the Manual Updates guide provided here
And if your site is under a caching plugin/feature please clear it after the updating.
Only then you can validate the site.