I have set everything up with the plugin but I do not see where to tell it which categories to appear it. I wish there was some documentation! Thanks!

In the right column in Disqus Comment System (plugin) parameters, there is the options:

Select categories to render the plugin
and
Select menu items to render the plugin

Didn't you see them???

No, I do not have them. My only choices are Display a comments counter/anchor link in listings (e.g. blogcategory) and Display a comments counter/anchor link in article view. I am using the K2 version.

Please provide me a link to your site.

I am having the exact same problem with the K2 plug-in. "Disqus Comments for K2 (by JoomlaWorks)"

If i disable the plug-in my 2 K2 blogs are fine.  As soon as I enable them, The blogs are all gone with the following error;

The website encountered an error while retrieving www.arkofhopeforchildren.org/seeds-of-hope/item/27-help-for-the-hurting. It may be down for maintenance or configured incorrectly.     HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request. ???

www.arkofhopeforchildren.org/seeds-of-hope          and

www.arkofhopeforchildren.org/blog-of-hope