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Just to add to this:

Adding an ALT attribute (alternative text) to all of your images is a usability best practice and can also help with your SEO efforts.

Here's a (fairly old) video from Matt Cutts, head of Google's web spam team, that highlights the importance of not ignoring ALT attributes:

http://www.youtube.com/watch?v=3NbuDpB_BTc

And here's an article from Rand Fishkin that briefly touches on the topic:

http://www.seomoz.org/blog/perfecting-keyword-targeting-on-page-optimization

Specifically:

"Alt Attribute - Surprisingly, the alt attribute, long thought to carry little SEO weight, was shown to have quite a robust correlation with high rankings in our studies. Thus, we strongly advise the use of a graphic image/photo/illustration on important keyword-targeted pages with the term/phrase employed in the alt attribute of the _img _tag."

To the best of my understanding, adding the rel="noreferrer" attribute to an <a>tag (i.e. attaching it to a link) just means that you don't want the user's referrer information (e.g. what browser, operating system, etc. he/she is using) to get passed along. </a>

<a>My guess is that it has more to do with privacy, rather than SEO. From a search marketing standpoint, I wouldn't spend too much time thinking about it, if at all.</a>

Just ran the example link that you provided through two independent HTTP response code checkers, and both are giving me a 200 response, i.e. the site is OK.

This question has been asked before on here; you're definitely not the first person to run into the issue.

One way to diagnose what's going on is to dig a little deeper into the crawling report that SEOmoz generated. Download the CSV file and look at the referring link, i.e. on which page Roger found the link. Then go to that page and look if your CMS is doing anything weird with the way it outputs the links that you create. I recall someone back in December having the same issue and eventually resolved it by noticing that his CMS put all sort of weird slashes (i.e. /.../...) into the link.

Good luck!