Thi is not a theme realted issue. As Tess pointed out Microsoft WORD is not web compliant and word processing programs are not the same as blog editors. WORD produces junk code.
Please go here and enable this setting Settings > Writing and select “ ___ WordPress should correct invalidly nested XHTML automatically” and then scroll down and click “Save Changes.” Then starting with your latest post, open it in the editor, make one minor change such as adding a space and then deleting it, and then click “Update Post.” Check your blog and see if it is back to normal. Note: You will only have to do this once on your blog.
I think you may also benefit from reading:
WordPress Formatting and Spacing
Space between lines
Space between paragraphs