Hrmmm... I don't have Word 2007, so I'm not sure how useful I'll be. But I'll try
You might have 'orphan' and 'widow' controls set for your paragraph style. Basically, these stop one or two lines of a paragraph being stuck on the bottom of a page, with the rest of the paragraph on the next page. For print publishing, that's a legitimate issue. For epublishing, it's not at all important, and the code will likely be stripped during conversion anyhow.
If you need some more active help, I'm happy to look at the Word document directly. Just let me know.