This is an error with the html on your webpage, not with firefox. Among other problems, your comment on the first line needs to be closed with "-->", otherwise firefox will parse the entire page as a comment.
To prevent (or diagnose) problems like this in the future, you can check that your html is valid at http://validator.w3.org/ ** Changed in: firefox (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to firefox in Ubuntu. https://bugs.launchpad.net/bugs/837646 Title: simple web page does not render in firefox (does in IE). Page is http://www.cs.cmu.edu/~rgw/TsaiDesc.html Status in “firefox” package in Ubuntu: Invalid Bug description: Web page in question is: http://www.cs.cmu.edu/~rgw/TsaiDesc.html ProblemType: Bug DistroRelease: Ubuntu 11.04 Package: firefox 6.0+build1+nobinonly-0ubuntu0.11.04.1 ProcVersionSignature: Ubuntu 2.6.38-11.48-generic 2.6.38.8 Uname: Linux 2.6.38-11-generic x86_64 NonfreeKernelModules: nvidia Architecture: amd64 Date: Tue Aug 30 12:09:41 2011 FirefoxPackages: firefox 6.0+build1+nobinonly-0ubuntu0.11.04.1 flashplugin-installer N/A adobe-flashplugin N/A icedtea-plugin N/A InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429) ProcEnviron: LANGUAGE=en_US:en PATH=(custom, user) LANG=en_US.UTF-8 SHELL=/usr/bin/zsh SourcePackage: firefox UpgradeStatus: Upgraded to natty on 2011-06-29 (61 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/837646/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp