Thumbnails

I made some portfolio pages with galeries. Because the loading of the pages did take to lang, I changed all the pictures, made them smaller.
It works better now.
But…now the seizes of the thumbnails are different.
They where all the same seizes before, but now the longer pictures, show longer on the page:
http://thecolourbubble.com/thecolourbubble.com/portfolio/little-pieces-of-happiness/

I have tried it a few times, did upload them new again, but still the same.
Settings are that my thumbnails should crob to the exact seizes.
I did not have this problem before in any of my pages, any idea what I can do?

Thank you

Ellen