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Computers on Network keep dropping off

Hello all,

We have a network with 100 computers (HP Desktops with Windows 7 Pro) all connected through Cisco Switches.  We have a Windows Server 2003/2008R2 domain.

About two weeks ago, a problem started happening where a couple of computers, sometimes only one, will drop off the network. Is happening for one computer much more than others.  Can happen multiple times a day.  Can happen for multiple computers at same time, but can also happen at different times.  The computers this is happening on are connected to different Cisco Switches. When it happens for one computer, other computers conntected to the same switch are not affected. All computers are connected, through ethernet, to a Cisco IP Phone which has two ethernet ports on the back. One for the wall and one for the computer.  When the problem happens, the Cisco IP phone is not effected at all.

When I say "drop off the network" here is what I mean:
The user complains that they have no internet and what ever program they are in says "Not Responding".  A lot of the times it is a network program they are working in, but sometimes it will just be MS Word 2010.

Upon diagnosing the computer, an ipconfig will show everything is normal.  Computer has IP Address, Default Gateway, Subnet, DNS's etc.  I ping the gateway but there is no response. I ping and it works fine. I ping the computers IP and it works fine.

After performing a reboot, the problem will go away, most of the time.  The one time I saw where the problem did not go away, the computer assigned a 169.x.x.x IP address.

Another way that I have fixed the problem is by performing a "Windows Network Diagnostics" and the troubleshooter finds this problem:  "The default gateway is not available".  The troubleshooter then disable and re-enable the network card and this fixes the problem.  The troubleshooters details of this problem is in the attached word document.  The doc refers to an ETL file for its diagnostics.  You have to download Microsoft's Network Monitor program to read this file. Did that but I couldn't find anything useful as it didn't give much information.  I would upload it but ETL's are not allowed on experts-exchange.

Yet, another way I have fixed this problem is by running the command:  netsh winsock reset. I did this along with a few other commands and rebooted the computer. Not sure if the commands fixed it or if it was simply the reboot.

Once the problem is fixed, no matter how I fixed it, it will stay fixed for a while but can return at anytime, one hour or one day or one week.

I've contacted our Cisco Support Company and they can't find any problems with the Cisco Switches.  No logs show any problems.

Where do I go from here to try an figure out the cause of this problem?
3 Solutions
Nick RhodeIT DirectorCommented:
What are your lease timers on the DHCP server?  Any event logs or something perhaps wrong with DHCP?
Mike RoeCommented:
Update NIC driver from realtek and make sure there is no sleep setup on the nic if no activity
Like Fredbear891 I would look for power-saving options on the PC's
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TravisMichaelAuthor Commented:
@NRhode:  Our DHCP Lease expiration is set to 8 days.  Checked the Event Viewer for the DHCP Server and there was nothing for DHCP are anything related.  We have DHCP Audit logs turned on and I checked each of those and found nothing bad happening in there.

@Fredbear891:  Haven't tried to update the driver yet, but Windows does not put the NIC to sleep due to inactivity. Windows only puts the NIC to sleep if the computer goes to sleep.  Here is where I got that info from: http://support.microsoft.com/kb/2740020

The computers are not going to sleep when this happens because it happens in the middle of users working. Plus we make sure they are not going to sleep through GPO.
I would first check the drivers on all of the machines, then check the switches. You also may want to monitor your network traffic. It is possible that something is occasionally locking up or causing a large amount of traffic to generate. Sometimes this could be something like autonegotiate causing issues on the network.

I reread your chunk about the IP phones. Are you sure there are no problems with the network ports on the phones themselves? Sometimes that PC port will start to act flaky. On a machine that usually disconnects, I would try to have the Cisco phone taken out of the equation for a while, and see if things are better. If they are, then you need to talk to Cisco about the phones, not the switches.

Are your Cisco switches configured for VLANs or are all devices on one subnet?
TravisMichaelAuthor Commented:
Update for this issue:

The problem continues to happen for random new users and for the same users.  On one user I have a static IP address set.  Since this computer has been on static, it has not once had the problem.  

From here, I found a pattern to the problem.  All of the problem computers are the exact same model.  HP Pro 3130mt MiniTowers. They all have the same Windows Image with the same Network Driver.  

Since finding this pattern, we have been updating the network driver for each person that has the problem.  We started this for one user a week ago and she has had no problems.  For everyone else, we started this yesterday.  Probably should have done this sooner due to everyone here saying to start with that.  

Will update after about a week.  Thanks everyone!
TravisMichaelAuthor Commented:
I am going to declare this problem as resolved.  The resolution was to update the NIC driver for each of the computers.  I admit that I was skeptical of this solution at first but once I discovered that each of the computers experiencing this problem were the exact same model of HP Desktop (pro 3130mt) and each had the same WIM Image deployed, I wasn't so skeptical anymore.

Thank you for everyone attempting to help solve this issue.
TravisMichaelAuthor Commented:
TravisMichaelAuthor Commented:
Contains the solution, which was provided by others.
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