Cable Internet Problem

[kls5834]

I came home last night, no connection on main PC. I have a wireless router for 2 other pc's in the house but I didn't check them because I called Comcast and got the recording that they were experiencing cable internet outage.
I come home tonight and still no connection on the main pc. I have reset, rebooted several times. I called Comcast. We took the router out and still no connection. Tech tried to renew ip address but we couldn't. It shows 0.0.0.0. However, and here is the tricky part, when we put the wireless router back in the loop, the other pc's work, but only if the main pc is out of the loop. If I connect it directly from the lan port on the back of the router to the back of the pc tower, not only does it NOT work, but then the other previously working wireless pc's do NOT work. If I unplug the main pc from the back of the router, then the wireless pc's begin to work again.
Yes, last night was halloween, but this is ridiculous. I believe it has to do with the ip address. Can anyone help?
Could the thingy in my main pc that the cat5 cable plugs into be bad? Is it a card or what? What would you call it? Hopefully, it isn't on the main board!
HELP!!!!!!

[z1p]

If connecting the PC to the router causes the other machines to lose there connection, it is likly that you have a problem either with the Network Interface Card(NIC) on your PC (the thingy the cat5 plugs into;) ), the cable, or the router.

The things to try are:
try another port on the router.
try a new ethernet patch cable (cat5).
try a new NIC (Even if your current NIC is on the motherboard (main board) you can add a separate NIC)

[kls5834]

OK, at the suggestion of a friend, I uninstalled the network cards in the device manager section, rebooted and let windows reinstall the drivers. It says "acquiring connection" but it never does.
Now, the other pc's on the WAN operate ok, even if I plug the cat5 cable from the main pc into the LAN1 slot on the wireless router. It won't connect whether the wireless router is in the loop or not.
I ran ping 127.0.0.1 and it said 4 packets sent and 4 packets received. My friend said this meant it was communicating correctly.
I still cant renew the IP address, it shows 0.0.0.0.
Any suggestions? If all else fails, I suppose I could just buy another wireless card and stick it in an open slot.
I opened the case and the the cat5 port and 2 other adjacent usb ports appear to be all on the main board, not a separate card.
Any other suggestions?

[bAdWaYz]

Just to see if it works you could try and static address that NIC. If a static address works then the problem isn't the NIC.

[kls5834]

Can you tell me how to do that? Are you saying to make up an ip address instead of letting it auto configure? How would I know a valid ip address? Is there a generic one that would work?
Thanks for the help!

[z1p]

See what IP addresses the other PCs get and use an IP address near theirs, but not the address they have for a default gateway. For example, if the other PCs are 192.168.0.25 and 192.168.0.27 with a default gateway of 192.168.0.1 then something like 192.168.0.50 would be fine.

[star36]

to see what TCP\IP and gateway addresses are do this:
start - run type in cmd
type in ipconfig /all
this will give you information on your IP sddress
Star

[kls5834]

OK, I tried that, didn't help to force an IP address in there. I bought a new ethernet card last night and put it in. I disabled the other network connections, enabled the newly found hardware, rebooted, and alas, no difference. Still shows IP as 0.0.0.0. I tried direct wiring my son's notebook to the cable modem (Motorola Surfboard 4100) and it would not connect either. Whats up with that? If no one has any further suggestions, I think I will just be a wireless card, stick it in there, and surf off the wireless router like the other pc's in the house. This is really freaky. If I connect the cable modem to the wireless router, all the wireless pc's will work. But if I direct cable it to any pc, it won't work. Yes, I have uninstalled and reinstalled the network adapters and the cable modem. Frankly, I am about to give up.?????????????????????????? Any suggestions anyone?

[z1p]

Did you try a different cable?

[kls5834]

Yes, I tried multiple different cables. Just as I was about to give up, b/c I had no where else to turn, I decided to use the Windows XP Restore function to reset all of the pc settings to a month ago. Eureka, that fixed it. I don't know what changed, but after restoring it, it immediately recognized the connection, gave an ip address, and everything worked as normal. Yes, I am curious as to what it could have been, but I am at my wits end and can't think of anything else it could be. I will continue to answer questions if anyone is curious about the situation and wants to figure it out. I just hope it doesn't happen again.
Thanks to all who tried to help me!