I must apologize for my slanderous remarks about Netscape not being able to handle PHP. My bad; Netscape and PHP are good bedfellows. It's poorly-formed tables that Netscape can't handle, which as I've had trouble with that before, should have been my first guess. Turns out Dreamweaver auto-added some code to one of my files (gasp! how GoLive-esque!) that closed off a table too soon, and poor little Netscape couldn't figure it out.
Nerd tip: If you have server-side includes that have opening tags (like <td>) without the corresponding closing tags (</td>), and you don't want Dreamweaver to close them off for you, go to Edit > Preferences > Code Rewriting, and uncheck the "Fix Invalidly Nested and Unclosed Tags" box. Okay. That's enough nerdliness for one post.