I looked at the skin and I found nothing of abnormal. I tested it on my site of test, but as I had no image, it had a strange behavior which gave me no indication.
The width of the plugin is fixed by the tweeter widget and it takes the width of the object in which it is contained. I do not understand why the box of the plugin twitterLink makes systematically some pixels furthermore than the other boxes (I tried with several values for widths of the side columns and it is similar).
It is possible to indicate a width to a widget, but it does not work...
I do not spend more time: the plugin work with other skin.
You can put the Twitter timeline in the center box.
Good luck. Congratulations
Christian
Réfléchis bien ... avant!