I have a TJ715 cable modem I use with cable america here in phoenix
arizona. the modem has worked great with 2 of my computers so I know that
all is well with the cable service provider and the modem. However, a
desktop of mine cannot connect. I'm MCSE certified and deal with networks
on a day to day basis. I've checked the lan cards and cables to insure
they are working. So here's the issue someone may be able to help with:
The cable provider issues a static IP address along with the gateway and
dns server addresses. When I configure tcp/ip on my laptop or my tablet
all i have to do is connect it to the modem and it within seconds the
modem and the LAN card sync up...i can browse the web as i please.
However, when i configure the desktop, I get transmiting signals from the
Lan card, good data signals from the modem but can't get the browser to
connect. I've done a clean install of XP professional on a virgin hard
drive and I still have the same problem. If I connect the Desktop to a
router/hub (netgear MR314) i am i able to access my local area network.so
i know the lan card is good. And if I connect my router to the terayon
TJ715 (cable modem) and configure the router with the static IP info and
have the router act as a DHCP server, then my desktop can access the
internet perfectly. Any suggestions on why the cable modem interacts with
some computers directly but cant with others?
I have turned off all firewalls and even shut down the modem for hours to
let it reset. It still won't work with that machine. Tech support for the
ISP said that they could see the computer on thier network but that it was
having trouble somewhere between the browser and the network side of XP. I
can't figure this out since it can see the trade files and see the other
computers on the network but will only connect to the internet when the
router is acting a DHCP server

My first question is why not just use the router.

As a fix, try changing the MAC address on the XP PC to match the MAC address of either the modem or the MAC address of the WAN side of the router.  I've run into the same problem on different operating systems several times and this seemed to fix it. 

Can't the router assume the static IP that should be going to your computer?  And if you have the router clone the registered MAC address...wont the ISP think the router is your computer.  Then with all that set up...wont the router dish out IP's for the LAN, and do all that magical stuff to get you browsing the web?