Oh my! Where on Earth did you get the idea to use the XHTML doctype and the XHTML namespace?
First remove those two lines completely from your new page or remove the first from your old.
Download HTML Tidy; the first version was written by the guy who wrote the HTML 3.2 specification. Configure it for HTML 4.01 strict, removing all FONT tags and transforming B to STRONG and I to EM and such. Run it on your target page.
Then make sure that the DOCTYPE looks like:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
and revalidate. Correct any errors if found. Tidy corrects for well-formedness and not validity.
Then read, mark, learn and inwardly digest http://www.w3.org/TR/html401/ before you work on any more web pages.