Problem with Uploading Images

I've been trying to add additional pictures to our products and there seems to be a weird problem I can't figure out. To clarify, I'm uploading my images through the UI by going to Catalog->Additional Product Images. When I try to upload images, the sort order of the images is completely random and doesn't make sense. It started out working fine and would add each new image I upload to the bottom of the list. I was able to sort the pictures by uploading them in the order that I want them. Suddenly, it started placing the images in random spots on the list. Instead of putting the images at the bottom it would put them at the top or in the middle. This completely ruins my sort order for the pics. What's wrong and how do I fix it?

Since there is no Catalog->Additional Product Images in a stock zen-cart installation, you might get better luck checking out the support thread in the contributions section for the plugin.