I have NextGen set to ignore Aspect Ratio and create 104x78 thumbnails. For some reason some thumbnails will randomly be smaller in width by 2-4 pixels. Seems to only happen to horizontal images. This creates an uneven thumbnail display page.
So I manually recreate the thumbnails which creates issue number two - sometimes the result is one Thumbnail will take an entire row in the Thumbnail display page. I can sometimes fix this by changing the sort order (that's weird) or I can always fix by recreating all thumbnails and resizing the randomly incorrect size nails, rinse lather repeat and hope it works or just give up.
GD Version : bundled (2.0.34 compatible)