JPEG in InDesign Problems

I'm throwing together a newsletter InDesign that requires putting in JPEG images. It looks fine in InDesign but when I export the image to Adobe reader the borders on my images change so that one side is darker/thicker than the rest of the sides. I hope that makes sense.. I just want all my borders to match.

I've tried replacing the images, making the images bigger/smaller, basically the side that has the thicker border just jumps to a different side with any change that I've tried so far.

Please help, thank you!

-Ashley