Windows 7, get's IP address from router but can't connect to Internet

stevehavert
stevehavert used Ask the Experts™
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This is a weird one....to me anyway.  

I have a client with a Windows 7 PC.  Starting three days ago, he suddenly could no longer access the Internet.  He has just the PC which is connected to a Cisco/Linksys wireless router.  The computer is getting an IP address from the router.  When I try to ping the router I get two replies from the IP address of the computer with the message, "Destination host unreachable" and two "Request time out."  

I tested the router with a different computer and it works fine.  Tried both a hard wire and wireless connection, same result.  Uninstalled both adapters in device manager and re-booted; same result.  Tried resetting the IP stack and tried a suggestion that had me create a new DWord entry named "ArpRetryCount" in HKLM\System\CurrentControlSet\Services\Tcpip\Parameters.  No joy.  

I've tried the system in Safe Mode, did a System Restore to before the problem started, scanned for spyware, cleaned up temp files.  I am at a loss as what to try next short of doing a Windows repair install.

Any ideas?
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Commented:
Hi have you tried assigning a Static IP to the workstation?

Also try turning the router off / on and deleting the current IP address from the DNS and DHCP.

Author

Commented:
Same result with a static IP.  I've tried this system on three different routers, same result.
Did your client report anything unusual that happened just before or after the failure?

What does ipconfig /all report? Has another wireless access point started broadcasting close by?

Does a cabled connection work OK?
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Commented:
have you done any major updates?

i.e. Service Packs?
Drivers?
Firmware?
Do all testing with a LAN cable first. Worry about wireless after you're confident that a cable network is working properly.

I've seen it happen in the past when a poorly-written antivirus program (or virus) installs a network driver that is intended to scan or sniff the network traffic, and it isn't removed properly or becomes nonfunctional, and this causes bizarre network problems.

The stack is referred to as "NDIS". Some viruses overwrite the system file "NDIS.SYS" with their own (damaged) version that causes problems.

Others are legitimate drivers that just don't work properly. If you go to Start->View Network Connections->Local Area Connection->Properties, do you see anything out of the ordinary in the "This connection uses the following items" list?

The only thing that should be in there is:

-  Client for Microsoft Networks
-  QoS Packet Scheduler
-  File and Printer Sharing
-  Internet Protocol Version 6
-  Internet Protocol Version 4
-  Link-Layer Topology Discovery Mapper and Responder
The clue that helped me solve this problem was 'antivirus program'.  There had been no recent Microsoft Updates and the client said he hadn't installed any new hardware of software prior to the problem occurring.  I decided to look at 'hidden' network adapter drivers in Device Manager by clicking 'Show Hidden Devices'.  There were a number of McAfee drivers listed.  I uninstalled McAfee, rebooted and voila!, we have Internet access.

Thanks for the clue.

Author

Commented:
I've requested that this question be closed as follows:

Accepted answer: 0 points for stevehavert's comment #37999959

for the following reason:

The prior comment was really the clue that I needed, but I felt it would be more helpful to list my comment as the solution because it was a little more specific to the problem.
Hi stevehavert,

My comment stated:

I've seen it happen in the past when a poorly-written antivirus program (or virus) installs a network driver that is intended to scan or sniff the network traffic, and it isn't removed properly or becomes nonfunctional, and this causes bizarre network problems.
You went into device manager and removed an offending network driver which was created by a non-functional antivirus program that was causing your problem. My comment was bang on the money.

I understand the first diagnostic step I asked you to perform was incorrect, and your comment reveals the specific solution to your issue. But on Experts Exchange you can accept your own post as the solution and award points to another facilitating comment. I think that my comment at least deserves some points.

Author

Commented:
Sorry Frosty555, I'm new at this grading / points thing.  I agree that you deserve some points.  Once I've done this a few times, I'll get the hang of it.

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