Having an anchor within a div that has the overflow attribute set to ‘hidden’ via applying the equal height column method creates a unique problem.  When selecting an anchor, the columns get “chopped off” at the top as if the entire div moved up and is chopped because the overflow = hidden property of the container.
The culprit of this issue lies within the column that has the structure below:

padding-bottom: 2000em;     /* X + padding-bottom */
margin-bottom: -2000em;     /* X */

When the named anchor is clicked,  the overflow:hidden atrribute and the above CSS structure kills the layout.
So if you need anchor tags in your site, avoid the equal height column method, there are other ways to achieve the same thing.

If interested, here’s some documentation on the problem.  Click here