Error

cURL error 6: Couldn’t resolve host ‘www.domain.’

This error occurs when the url you enter for your comment isn’t valid. Check to see if you have omitted a period (.) or misspelt your domain

A feed could not be found at http://domain.com

This means your site might not have an auto-discoverable feed.
See this article on ProBlogger about feed autodiscovery

You could also register your site url here and once verified, you can specify your feed location and ajax commentluv enabled blogs will use that value instead of trying to find it automatically.

cURL error: No response from host

If your url is correct then this means your hosting is not responding, your site could be down or it could be too slow to load. Check your site loading speed at Internet Supervision

Your links are showing as numbers on the stats page

If you are using Feedburner then this happens because you have click tracking on. See this article on turning off Feedburner link tracking