For anyone else that has an issue with ISOLINUX, the SYSLINUX site has this link http://syslinux.zytor.com/hardware.php
for hardware compatibility.
It lists PCI cards that are not compatible no matter what.
If you have this problem with other installs and you get an isolinux error message you can also try the syslinux mail list by going to this page: http://www.zytor.com/mailman/listinfo/syslinux
and subscribing to the mail list. The mail list does not accept HTML formatted email messages so be sure you use a mailer that sends plain text. You can also read through the "SYSLINUX Archives" by month for threads on your particular error.