Categories Don’t Display Links?!

For some reason (and I’ve seen this on other WordPress blogs too) when viewing a post via category or archive link, the embedded links in the post don’t show up.

An example is this:

Say the word “quack” is a link to something and is located in a post. When viewing the post from the index page, or from the specific comments page, “quack” shows up as a link. BUT when viewing the post from the category page or archive page, “quack” shows up as text, but not a link.

Why? How can I change this?

Thanks guys!