Keeps losing carriage returns

I’ve created a table containing content that includes carriage returns at the end of sentences. When I publish all looks ok, but if I then make some further changes and publish again, all of the carriage returns are removed from the content within the tables. Carriage returns outside of the table are still ok. This is on a new install of wordpress, the only other plugin installed is ‘WordPress SEO’, so I don’t think it’s a conflict with another plugin. Any ideas what I can do to sort this problem?

http://wordpress.org/extend/plugins/mce-table-buttons/