When retrieving resource strings from the ResourceStringLocale table nopCommerce converts the ResourceName to lowercase.
However when adding/editing a Resource in the Language interface (admin section) only case sensitive checking is done. This way it is possible to save a duplicate ResourceName.
i.e.
both cart.Checkout and Cart.checkout can be saved.
When loading the resource in the dictionary the resourceName is converted to lowercase (localResourceManager.cs). this causes a duplicate key exception and the frontend will crash on every page.
Regards,
Dennis Evers
Coders4you