Does this page use valid XHTML?

This website is very simple, and probably looks ok in your web browser, but it contains invalid HTML. This page might look ok in your browser, but it might choke on a browser that is less tolerant of coding mistakes. Can you find the invalid HTML on this page? Try this:

1. Look at the XHTML source. See if you can identify the invalid XHTML before running it through the W3C Validator. Hint: There are 2 examples of invalid XHTML on this page.
2. Run this page through the HTML Validator. Did you find the same mistakes that the Validator found?
3. Correct the mistakes found by the Validator, save the file, and run it through the Validator again.
4. Repeat steps 2 and 3 until the page validates.