Is there a way to prevent DNS lookups?

I have a system that a previous administrator "disabled" internet access on. Now we want it to have internet access, but I can't figure out how they did it. Here are the symptoms:

PC is configured for DHCP and receives an IP address and correct DNS entries.
PC can ping and tracert to any IP address.
PC cannot ping or trace to an external hostname: "could not find host XXXX"
PC can use nslookup to resolve domain names.

I'm thinking there is a registry key or some connection specific setting that was changed to prevent this. I can't figure out what is causing this issue.
leviatdrAsked:
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vervenetworksConnect With a Mentor Commented:
You may try to reset the TCP/IP stack using WinSockFix http://www.softpedia.com/get/Tweak/Network-Tweak/WinSockFix.shtml

NSLOOKUP does bypass the local DNS cache, and directly queries the primary DNS server.  You can specify an alternate server by using the command "server <servername or IP>"  My bet is a broken stack.  Any antivirus software or local firewall software you could try disabling as well temporarily.
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vervenetworksCommented:
The easiest way to prevent internet access is the use of a proxy server in Internet Explorer.  Open IE, find Internet Options, typically under Tools or Privacy depending on the version.  Then to to Connections tab, and LAN Settings.  Uncheck the proxy if checked, and test.
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leviatdrAuthor Commented:
I already checked that and there is no proxy set.
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vervenetworksCommented:
Is the primary DNS server on the PC internal to the network?  It may be using some type of DNS proxy through forwarding, such as OpenDNS.  You could try setting DNS to an external server, and test from there to see if the problem lies with the server.
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leviatdrAuthor Commented:
Primary DNS is on the same network. I set the DNS server to both the local dns server and resolver1 at opendns. Same results. I can nslookup but not ping by hostname.
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vervenetworksCommented:
Does the server exhibit the same behavior as the workstation?
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leviatdrAuthor Commented:
No, the server and other local workstations resolve names just fine.

After digging through the event viewer, I'm finding Userenv ID 1054: "cannot obtain the domain controller name for your network, an invalid argument was supplied". I know this is a DNS issue, but I can't figure out why nslookup works but standard resolution doesn't. Does NSLookup bypass the local resolver?
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akahanConnect With a Mentor Commented:
If you go to

Control Panel / Network Connections , right-click on the NIC you're using, choose Properties, choose Internet Protocol (TCP/IP), click the Properties button, click the Advanced button, and then the DNS tab, do you see anything unusual?

Tried uninstalling and reinstalling the NIC?  Uninstalling and reinstalling the TCP/IP protocol?
Ensuring that the firewall is not blocking UDP packets to port 53?
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leviatdrAuthor Commented:
Winsock fix did not resolve the issue. I'm going to try reinstalling the NIC to see if that helps.
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leviatdrAuthor Commented:
Issue unresolved. User formatted machine. Thanks for trying.
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