Read more link doesn’t always work

I have two “Random Content” widgets in the left-hand sidebar. They each display a different “group”. The one for “Author Spotlight” displays posts that contain the “More” tag. The random displays are fine, showing only up to the “More” tag.

The problem is that apart from a couple of them, clicking on the “Read more” link results in a “Page not found”. Since a couple of them do work (for example, keep refreshing the page until “Jeff Bayone” is displayed and click the “Read more” to see it work.

Essentially, I’m using posts/pages the way posts are meant to be used: A brief excerpt is displayed and if someone wants to read the whole thing, they click the “Read more”.

The page I need help with: [log in to see the link]