Different Sized Images Fix:
Cool, so I had the same problem. I was looking into the thumbnails and found out that these were the problem for me as well.
So, I went into the NextGen Gallery Options and under Thumbnails, I changed the ratio to something square (so I did 75 X 75) and still kept the “Ignore the aspect ratio” checked on.
Then, I went back to the gallery and selected each thumbnail again just like wendlz did. However, do not crop the thumbnails against the edge of the image or you may not get a square thumbnail with different image sizes. I kept getting some with 75 X 74.
Then I updated my page that I posted the gallery on.
Checked the source page and all ratios were fine. All fixed!
Wendlz fix will work if all your images are the same size.
Hope this helps. Thanks guys!
