It means that either file l/components/com_jcomments/js/jcomments-v2.1.js?v=2 doesn't exists on your site (may be JComments isn't properly installed) or some server settings blocks request to this file.
That's correct. I've only got jcomments-v2.1.js, dunno anything bout v=2 (or am I saying something really stupid here)?
What permissions is it supposed to have?