Brian
Is your dhcp server connected to your lan malfunctioning and redirecting your packets throught he wrong gateway? Har har har
That cable modem guy was frickin hilarious at your house when he was making up some BS to explain why it wasn't working.
Good luck with that thing, let me know if you need to back up your files, if you can get connected with the cable modem we can back up your stuff to the site while you rebuild.

good luck

-Rob