Something that I've come across a few times when working on SharePoint/ MOSS 2007 features. When importing a Page Layout the ASPX some times becomes corrupt. You end up with additional HTML inserts once it's been imported into SharePoint. The corruption is in the form of HTML tags, outside the last </asp:Content> tag. Well it turns out that the problem is caused when you import an ASPX that has a </asp:content> tag it'll happen.