Strange Networking Problem in XP- Stuck in Automatic Private Address mode.

[Aphostile]

Usually I'm the one solving people's PC issues as I've been avidly using PCs since the eighties but this time I'm beyond stumped with a strange issue on my own PC.

I have a P4 2.53ghz with 1gb of DDR ram, a NIC which is integrated with a SiS 648 chipset mobo (it's an ASUS P4S8X). Can't see how it's relevant but for the sake of completeness a GeForce 4 Ti-4600 video card and an Audigy 1 sound card.

The issue is that no matter what I do, the NIC, a USB connection to the cable modem, or other PCI NIC cards I put in- *nothing* will recognize the cable modem attached. It will not recognize any external DHCP server- it will not connect to external routers I have tried plugging into it either. Whenever the network cable is plugged in they will go into Automatic Private Address mode and get stuck there.

I tried disabling APIPA in the registry. It would still come up in this mode except the IP address would be 0.0.0.0 instead of one of the 169 series IPs. I have tried working with Earthlink Support, doing all basic trouble shooting, releasing the NIC from the command line, all that stuff. Earthlink Support ended up stumped after trying every trouble shooting thing they had.

The cable modem and routers are not the issue because they work fine with my older system which I am posting this message with currently. It is a Motorola SB4200 cable modem but it is definitely working properly. The problem also happened with both a Linksys and a SMC router which have DHCP servers.

The last time I got this issue I ultimately got fed up and reinstalled XP. It worked for awhile but strangely the issue has reoccurred and I really would rather not reinstall XP each time it happens.

Also I know the Motorola USB cable modem drivers are bug ridden. I tried them last time the issue occurred. This time they are not installed and never were until after the issue occurred so they are not the cause either.

Does anyone know what could be causing this and how to resolve it?

Thanks!

[Aphostile]

BTW- everything is patched up to date on the system- it's XP Home edition with Service Pack 1 and then some.

[zen2002]

When you installed other network cards what process did you use to un-install them ?
If you just "put them in and took them out " windows will assign a new IRQ everytime.
This happened recently to a friend of mine and the solution was to go into the Bios and choose "optimal settings"or "default settings" this then reset the pooter to it's origional state and everything worked OK.

[Aphostile]

Well I will give it a try but I had several different IRQs assigned to the various cards... 17.. 19 and another I forget and the issue still happened. I also tried disabling the on board card in bios then booting then rebooting and renabling.

It's worth a shot let's see how it goes. Thanks for the suggestion !