Network goes down when one particular computer connects

15 pts.
Tags:
Network monitoring
Network routers
Network testing
Routers
I have 5 computers sharing a network / sharing a common router but recently I'm having a problem in which when one particular computer is opened, the whole network goes down and none of the computer is able to connect to the internet. What could be the reason for that? Is it because of some kind of virus in that particular computer? Please help me in this matter. I have lots of important data stored in the computer and most of them are network based.

Software/Hardware used:
home router

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Dear Sushant don’t panic. Nothing will be lost, you may get all of your data, just keep your mind and brain cool….. There are a number of reasons why this may have occurred!
NOTE: Before doing anything you must take all necessary data backups else it may cause serious problems.

  1. The particular computer may affect by virus
  2. It is possible one or more service(s) may stop suddenly
  3. Corrupt any system related files
  4. All of a sudden other 3rd party software may creates problems

First you have to disconnect the particular affected computer from your network.
Now check one by one (as told earlier), you may use in-built system checker tools or licensed utility software to find out the problems. Though you didn’t disclose which OS your using, I guess you may know how to use these tools of software.

————————————-

I disagree that this has anything to do with a virus.

Your symptoms are more indicative of a layer 2 (data-link layer) issue, not of any applications or services (viruses or otherwise).

If the network is fine without the PC plugged in, and cabling it in almost IMMEDIATELY crashes EVERYONE’S network connection, you my friend have a bad NIC on that PC.
The NIC, when connected, is trying to contact a DHCP server, which is a BROADCAST packet in IPv4, and the fact that the ENTIRE network drops means you’re experiencing what we call a “Broadcast Storm”

Easy fix: Replace the NIC in the PC and try again.

Discuss This Question: 13  Replies

 
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  • jinteik
    What you can do is to do elimination process. 1. If you know which PC goes in and brings down the network, could be that PC is being infected. 2. Scan the PC with updated antivirus. If you cannot, remove then format (if necessary) What happen last time to my company network is some programmer created a program and it was also at the same time caused a virus / caused my network to go crazy. Every PC will point to that PC to get out / became the gateway. So after removing it from the network, it was back to normal.
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  • carlosdl
    Sushant20, can you clarify if the whole network really goes down (computers can't talk to each other at all) or it's just the internet what stops working ? What do you mean by "one particular computer is opened" ? Does this happen when you turn this computer on, or when you try to access some shared resource on it ? What are the operating systems involved ? Is this a workgroup or a domain environment ? I agree, one possible cause would be a virus infection, but the more details you provide the easier it will be for the community to help you.
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  • petkoa
    When I had similar problems on my network, twice it had been a faulty NICs, once a faulty switch port and twice infected PCs (but never a single infected PC)... So I'd start with the hardware check. Good luck
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  • Sushant20
    Actually the situation has gotten worse...now even the command promt and task manager is inaccessible. I can't acesss the system file. The virus lets me access and install common file but doesn't lets me install anti-viruses. Sometimes I can access the internet (everything is working fine) but when I Google info "How do I remove .exe virus" the browser stops working. Smart virus indeed.
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  • mpez0
    Check your IP addresses (
    ipconfig
    ) and make sure there are no duplicates. If you're using DHCP, have all the clients renew their leases, especially the suspected bad one.
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  • Dwiebesick
    If you think you have a virus, start with scan from a rescue disk. Here is a link that talks about some http://www.raymond.cc/blog/archives/2008/12/11/13-antivirus-rescue-cds-software-compared-in-search-for-the-best-rescue-disk/ You can also download from another computer VipreRescue (live.sunbeltsoftware.com), ComboFIx, Malwarebyes and scan, and then scan with another product.
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  • Subhendu Sen
    Are you able to access safe mode without networking? Try this one ....
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  • Sushant20
    [...] Network goes down when one particular computer connects [...]
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  • Betojoe1980
    Good Morning experts, My sugestion shoul be firstly: Can you explain us if you are using a router as a DHCP ? Another sugestions is, if you are using in the Router the same time with a server, like Windows or Linux server ? Because, if You are using Windows server it can start the DHCP server when you restart the server, it normally happends when we want to update or solve any problem, and in this situations you will get to DHCP servers working ( i mean DHCP of Router and DHCP of a Server) in the same LAN, and everything goes DOWN. If none of this solve your problem, Please Check Now another situation, If you are using a Static IP in your LAN, and Check wich IP is this computer using and compare if there is another PC using the same IP address, even if you are Using DHCP, Please check if this PC get IP static and compare for the rest of others IP addresses. Check also if this PC is not using a a virtual Machine, then check what kind of virtual machine is there and control also all Ip, because, normally the Virtual machine use NAT, But if is a server Run inside it can crash your LAN. Check all aplications running in this Computer, Please Check all the Applications. Finally, is not a Virus in my point of view, because virus can get your LAN slowly, but down i never saw before, But everything can happend. I hoppe that it helps you. Alberto
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  • Snapper70
    What is the IP address of the computer that causes the network to go down - and what is the IP address of the router on the LAN side? Is there any chance that they might be the same? A device on the network with the same IP as the gateway/router (be it server, workstation, printer) will cause issues like you've described.
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  • Sixball
    (My vote is broadcast storm)
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  • Levi
    I had the same problem yesterday. I have a network of 1 server and 2 additional workstations, it took me 2 days to find out that only when my server is plugged in to my router, no one can access the internet but still able to communicate one computer to another. (Another strange thing was that I was able to ping out to the internet but couldn't open a browser connection) I didn't assume that the problem is with the NIC because I have 2 NICs on my server and both failed... Finally I realized in the Task Manager that a process ‘s.exe’ is running with a tremendous amount of cpu and when I tried ending it would immediately restart. So I Googled to find out that this is a virus. So I installed Malwarebytes and cleaned the computer (I had to run it several times until I finally cleaned it) And now everything is up and running fine!
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  • N1983
    Your PC is virus infected, scan it with an anti-virus software.
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