Network Fluttering

[Will12]

Windows 2000 Server network with 2000 and XP Protocols. Patch Panel and Switch, 31 users. 2000 server is 1st DNS
Connect 1 (WIN 2000) user to network and it appears to be looking to resolve an Address because the network connection immediately starts to flash and brings the entire network to a crawl. Unplug user everything goes back to normal. Tested wire and network seems fine. Changed user to another socket and works fine. Could be just the wall outlet, I know, although it tests fine.
Used a 2000 machine with a 10Mbps card on a second socket works fine. Connected an XP Pro with 10/100, same thing as the other socket with the 2000 user. Turned the system off and unplugged the patch panel connection. network went back to normal. Recoonected, with the XP Pro system shut down, the patch panel wire. Network sees the connection and the entire network begins to flash again and the network slows. Disconnect and everything goes back to normal. Anybody got any workable ideas?

[NooNoo]

umm different computers, different cables, only thing in common is the jack?

[Will12]

umm different computers, different cables, only thing in common is the jack?

If it were only that easy. Nope. Different jacks, different wires, same switch, different ports, different ports on the patch panel.

Perhaps an idea. Each of the systems were brought up under Workgroup and migrated to the Domain. Pretty standard stuff. Each were updated originally from a different, but same for each, ip for the internet.

[JeffO93]

We had a Dell that brought down the people next to it.
It made NO sense at all, but we disabled the integrated NIC and installed a 3COM 10/100 and the problems went away.

The bad card checked out fine, but it was still the culprit.
The two computers plugged into the panel adjacent to the Dell went haywire, but the rest of the computers plugged into the same panel and on the same hubs were also fine.
Our expensive systems tools isolated the network problems to the one Dell but couldn't find anything wrong with the NIC. Dell refused to give us a replacement. I threw in a surplus NIC and called it quits.
That was four months ago and still no more problems.

Years back, I had a customer with mysterious problems that were related to Norton AntiVirus. Everything was fast, even when the two computers were connected to the server and humming away. Only when their Legal database was going out on the Internet link did it all bog down to a crawl. We suspected it was the Legal databse software. It ended up being Norton on the server not working well with the types of transfers the Legal software was doing. They got McAfee AntiV and the problems went away.

Can't tell you what your problem is, but these past problems might point you at new things to look at.

Could someone have run some network commands that might be screwing things up, like static arp-to-mac stuff? If someone on another machine does an arp static map to the NIC in question, it might explain why there's sometimes a problem with only that card on that machine.

I had a machine that couldn't connect at 100Mbps, and couldn't connect to Exchange server. I ran the following on it to fix it. (And this refresh script has fixed numerous other machines.)
net use * /d /y
NET USE /persistent:no
nbtstat -R
nbtstat -RR
ipconfig /release
ipconfig /flushdns
ipconfig /registerdns
arp -d *
ipconfig /renew

Make sure you have a list of all mapped drives and persistent connections beforehand. You might have to put some back manually, depending on how you guys set things up.
If you put all this in a batch file, it's an instant to run.
When it fixes things and I'm asked what it was, I just shrug and say, "I don't know; something on the list".

Also, there have been a few times that a computer couldn't connect no matter what I did... until I deleted the clutter of shortcuts that tend to automatically build up in Network Places. If one or a few is pointing to an obsolete place, Windows still tries to reach out and tap it. I hate those links!

Try adding this reg entry to see LAN errors:
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Contro l\Network\Connections\StatMon]
"ShowLanErrors"=dword:00000001
Then in your network card properties, make sure the checkbox to "Show icon in notification area" is checked. Then you can right-click the icon in the Systray, click Status, and see the errors on Sent and Recieved. For some reason the errors are a bit low in the window pane, but you can still read them. It's free, it's Microsoft, and will tell you when data transfers are screwed up on the local PC.

[Will12]

Thanks. I had some similar thoughts but was afraid I was going too far off the wall with the on board NIC. Nice to know other crazies are out there too. I have had some trouble recently with these cheap on board NIC's. 3 COM has bailed me out of several situations over the years. Oh the prices we pay to save some money.
Great ideas, I'll work on them and letcha know how it goes. Thanks for the shove, hopefully in the right direction.

[Cyphrr]

I had a similar problem twice with a fiery print server. The switch showed a lot of network activity coming from the print server, but nobody was printing to it. Because of this, it took everyone off the network. As soon as the print server was disconnected, people could get back on the network. The tech support for the fiery claimed that the unit had a virus on it, and that they needed to send a tech out to wipe and reload it. Sure enough after they did, problem went away.

[JeffO93]

The case I gave of the Exchange server not being reached, and the Norton AV+Legal software reminds me of my new axiom:
"If you've looked 'til you're blue in the face and can't find anything wrong, you're probably not looking in the right place."

With the Dell NIC, it was right there. But many other problems can be caused to one PC from somewhere other than the problem PC.

Good luck!

[Grateful_Dad]

Ok, I know this is probably not your problem , but....
A friend had a similar problem with a home network. They had tried 3 routers before callin me, thinkin they had a bad one. One machine would start activity as soon as it was plugged into linksys router and choke out network. It was blaster and was scanning for other pc's to infect - it got 2 out of 3 of his computers. Found it when i put my laptop on router and norton popped up alert. Check for viri and what not... Just in case
HTH