Many different ways of writing HTML are largely accepted, even if they’re not “standard methods”, and some methods are deprecated. HTML has evolved, and a closing table row (</TR>) tag is no longer required, along with self-closing tags (e.g.: <BR />).
While there may be other issues causing it, HTML loaded using jQuery seems to be subject to more specific rules when parsing. Maybe someone can be more specific, but I wanted to put this out here since I was confused and found nothing after searching. In this case, make sure that your anchors in the HTML code that are loaded by jQuery contain quotes after HREF (eg: <A HREF"link.htm">). Modern browsers read it without quotes, so long as there’s no space. HTML code parsed using jQuery seems to be less flexible.
So something I never learned in school, but should be kept in mind for troubleshooting that anyone but a pro might not know: If something doesn’t seem to work, always fall back on more robust code, even if you want to streamline.