DHCP clients cannot contact/connect to Domain Controller

I have been working on this for the last couple of hours now with no luck.  I have an SBS 03 Prem R2 box and as of this afternoon network connectivity has been down.  The client computers cannot connect to the server at all.  I can ping the clients from the server but the clients cannot ping the server.  The clients can ping each other and the router though.  I have checked all of the usual suspects.  First checked the cable from the server to the switch, its good.  Tried a different port and it didn't change anything.  DHCP is running, DNS is running, IPSEC is running.  There have been no major changes done in the last 24 hrs.  I went as far as going out and buying a new NIC and I'm still having the same problem.  I also bypassed my switches and connected the server to a different switch and connected my laptop to the same switch and tried to ping it with no luck.  I am at a complete loss here and I don't know what I am overlooking.  Any suggestions??
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kgeiger81Asked:
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Michael OrtegaSales & Systems EngineerCommented:
Disabled firewall? Disabled security software, e.g. Antivirus with Firewall features? You say IPSec is running. Are you actually using IPSec policies? Tried disabling those?

MO
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Michael OrtegaSales & Systems EngineerCommented:
Also, have you checked the event logs? Anything stand out? I've seen the IPSec driver go into Blocked mode after some windows updates. Typically rebooting the server will resolve the issue.

MO
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kgeiger81Author Commented:
Firewall is disabled, antivirus is disabled, I'm not running a IPSec policies and I also tried disabling that as well.  I checked the event log many times and there is nothing unusual showing up.  I have rebooted 3 times already with no change.  I just tried running a packet capture on the Nic and the report is showing DNS queries from the clients to the server IP but they still cannot connect.  
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Michael OrtegaSales & Systems EngineerCommented:
Your server and clients are all on the same broadcast domain, right? Same subnet?

MO
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kgeiger81Author Commented:
Yes they are, same domain and subnet.
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Michael OrtegaSales & Systems EngineerCommented:
Can you post the capture? If it's a .cap file just rename it to .zip and upload it. Don't try to zip the .cap file, because the file upload features on EE will scan the contents and block it.

MO
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kgeiger81Author Commented:
Attached is the packet capture which only includes 100 packets.  It opens in somewhat formatted in wordpad.
Packet-Capture
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yousef_adCommented:
sounds like a virus
something block the connection between the server and your clients...chech the antivirus..some of viruses do that..scan your files online..
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Rob WilliamsCommented:
Improperly configured Routing and Remote Access can cause this problem. If you have only 1 NIC you can safely shut this down in the RRAS console. If you do so and have 2 NICS it will disable Internet access.
After re-enabling you will need to re-run the Configure E-mail and Internet Connection Wizard, and if you use a VPN you will need to re-enable it. If it did temporarily fix the problem it was likely due to NAT being enabled when the VPN was configured. Use the following instructions for the VPN:
http://www.lan-2-wan.com/SBS-VPN-instr.htm
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kgeiger81Author Commented:
I didn't think about the possibility of it being a virus.  I had a problem about six months ago where i got a virus and it didn't allow me to open a specific console.  Anyhow, RobWIll I am only running one NIC in the machine and all of my VPN connections are handled by my Sonicwall router so the routing and remote access service is already disabled.  I will run an online scan when I go back to the office this morning.  Thank you all for your suggestions thus far.  I will post my findings after I run a scan.
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Rob WilliamsCommented:
You mentioned buying a new NIC. Though I appreciate the problem existed before this, you MUST use the Change server IP wizard, even if making no changes, after installing, and then run the CEICW.
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Michael OrtegaSales & Systems EngineerCommented:
Can you get a NetMon capture and post it? Not enough details in the capture you posted.

MO
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kgeiger81Author Commented:
I ran a virus scan and it did find a few bugs and I removed them.  I checked to make sure that RRAS was not running and for whatever reason it was running.  I ended up disabling it and restarted the machine and that ended up being the problem.  I'm not sure why that service was enabled and the only thing I can think of is that one of the bugs could have enabled it.  Thanks for all of your help.
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Rob WilliamsCommented:
Thanks kgeiger81. Good to hear you were able to resolve.
Cheers!
--Rob
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