I don’t know if it’s the plugin or my hosting company but I cannot get the plugin to work without this “Internal Server” error message. When I deactivate it my website comes back minus the product pages.
You also posted about this exact same issue over herehttp://wordpress.org/support/topic/plugin-wp-e-commerce-wp-ecommerce-internal-server-error-message
You need to switch hosts and mark both of these as resolved or delete one thread.