Weird line breaks on Kindle?!?

[echthemoderate]

So, I've trawled the web for this and found nothing. Y'all are my last hope.
I've been using MobiPocket to create the .prc file for my Kindle book. The source for my text is an html file.

Oddly, when I view it on the Kindle, there are strange line breaks not present in the code. Even more strange, these only occur on some font display sizes. Additionally, each font size has it's own unique set of anomalous breaks.

It looks like this:

Words words words words words
Words words words words words

Words words words words

That blank line shouldn't be there. I hope this makes sense and that someone can help me. I am all out of solutions.

Thanks!