What the ??? is going on here?

[classicsoftware]

My PC lost connection to the Internet. Ok, I re-set the router and the cable modem and no joy. Nobody else in the house could access the PC which acts as a data server. Swapped the cable, no joy. Check under IPCONFIG and there was no IP address.

Disabled the on board NIC in device manager and installed a PCI card. Everybody is happy...

Five days later the same scenario repeats itself this time with the new PCI card. I figure my luck is just running bad and I had to replace the PCI card after all, they only cost $6.00. Just for the heck of it, I enabled the on board card and it works....

Does anyone have a clue, because I don't....

[jlreich]

Were the other machines not getting an IP as well? Or just that one? Was it getting a private IP at least? Could you ping localhost?

Since you are losing the connection with all the machines on the LAN, I would lean towards the router having the problem. Even more so if there is no IP being assigned to any of the machines.

[Budfred]

When I got up this AM, my connection to the internet was gone... My modem indicated that I was still getting DSL, but no Internet... I was planning to call my ISP later today, but tried power cycling the modem one more time and it worked...

It is probably not the same kind of thing, but I will ask anyway... did you contact your ISP?? The fact that networking was down within the house suggests that it is something else...

[classicsoftware]

Were the other machines not getting an IP as well? Or just that one? Was it getting a private IP at least? Could you ping localhost?

Since you are losing the connection with all the machines on the LAN, I would lean towards the router having the problem. Even more so if there is no IP being assigned to any of the machines.

No only my pc. With no IP address, I could ping nothing.

[jlreich]

With no IP address at all, with both the onboard and PCI NIC, it points to a software problem.

You may want to try resetting the TCP/IP stack. Here (http://support.microsoft.com/kb/299357) are the instructions to do it manually with the NetShell utility, or there is also the download that will do it for you on the same page. Either way will reset the TCP/IP stack to the way it was when the OS was first installed. More or less reinstalling it.

[Variable]

Yes, 0.0.0.0 usually a firewall or blocking issue. I think your machine is sending out the discover packet but getting a incorrect response. If it saw no DHCP server at all you would probably get an APIPA 169 address. I would run a packet sniffer if it happens again and see if you see the DHCP packets go out and any response. It is probably a blocking issue but reinstalling the tcp/ip stack wouldn't hurt although, since it is your machine, I doubt it has spyware.

[karthik]

At office: When ever there is no internet connections we could switch off the modem for few minutes and then try again and it works.(basic steps)
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When you say that is no ip address configured to you PC and then later you installed a new PCI card then it worked, make be it is pointing towards the motherboard interface rather than PCI card itself.(or other components)
Instead of complicating the issues try making other machine as sever then see whether this issue still exist.
In the meanwhile check the existing machine.

[classicsoftware]

My thought would be that:

IP address=0.0.0.0: Either there is a firewall or spyware blocking the traffic or the NIC itself is bad.

IP address=169.x.x.x: Means the NIC is working fine hardware wise and there is a problem with the DHCP server or TCP/IP stack.

What I don't understand is why it would NOT work on Thursday, but work on Saturday? What I also don't understand is why the PCI NIC worked on Thursday, but stopped working on Saturday?

[jlreich]

My thought would be that:

IP address=0.0.0.0: Either there is a firewall or spyware blocking the traffic or the NIC itself is bad.
Agreed, except for the firewall. Even if the firewall is blocking all network traffic you should still get a private address and still be able to ping localhost. Although there seems to be an exception to this as indicated by Variable - Yes, 0.0.0.0 usually a firewall or blocking issue. I think your machine is sending out the discover packet but getting a incorrect response

IP address=169.x.x.x: Means the NIC is working fine hardware wise and there is a problem with the DHCP server or TCP/IP stack.
Agree about the DHCP server, but if you have a private IP, TCP/IP should be fine. You can confirm this if you can ping "localhost".

What I don't understand is why it would NOT work on Thursday, but work on Saturday? What I also don't understand is why the PCI NIC worked on Thursday, but stopped working on Saturday?
Yes that is the odd thing. I hate intermittent problems, they are so hard to diagnose sometimes. :(

If it had only happened to one of the NIC's I would say the card is bad, but it happening to both more or less rules that out. The only other hardware issue I can think of that would cause this is possibly bad caps on the mobo.

When you had the problems did you happen to look at the link LED on the NIC to see if it was on?

I still think it is software related though. I would start by resetting the TCP/IP stack just to be sure since it is easy and doesn't take very long to do.

To rule out the firewall if it happens again disable it and "ipconfig /renew".

Also do a "ipconfig /all" to see if it is at least showing a NIC installed.

Another thought, did this coincide with recently installed windows updates?

[mjc]

Another thought, did this coincide with recently installed windows updates?

Or any other network related (AV/firewall/etc) updates?

[Variable]

Well when I see weird intermittent problems I almost always suspect hardware. If it was software, the issue would probably be consistent. Assuming nothing changed during the episodes of course.