columns out of alignment.

hi when i add more than 2 columns the last column is always out of alignment. i can correct it using firebug by changing the:-

< div class="column one-third omega" >
< a class="cboxElement" rel="lightbox" href="/wp-content/uploads/2010/09/Fessy_10.jpg" title="DRH1" >
‌·
< img src="/wp-content/uploads/2013/02/fessy10_thumb.jpg" alt="">
< br>
‌
if i move the < br > and put it above the < img src > it aligns correct but cant figure how to change the css to reflect it.

i had to alter the homepage around as it was doing the same thing, now its happening in http://www.profdavidhughes.com/gallery for example.

(had to add spaces to be able to post they not really their)

help would be gratefully received