Issue With Portfolio Images

http://smartjewelryshopper.com/ODBG/portfolio_category/top-10/

Why aren’t the images scaled and aligned properly in the category page for portfolios? If you click the url, you will see that there is a blank space under the first thumbnail.

I had tried using the same sizes and even different sized images for the following image 450X330px, 430X330px and even other image sizes for this file.

The Annonying thing is that the most of the others images you see on that page also HAS the same width and height 450X330px but they don’t cause problems of misaligning the entire thumbnails layout at all.

Why is this happening only for certain files?