DHCP Not Working / Possible Virus Problem

A user on my network got a virus called WinAntiVirus Pro 2007.  Since then I've had a handful of machines that are no longer pulling the IP address from the Domain Server.  I was able to remove the trojan using AVG Antispyware, but still the PCs are pulling the incorrect IP.  

Right now I'm assigning a static IP address to keep them working, but I need the machines to pull from our DHCP (domain controller) again.  Anyone have any suggestions?
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captainConnect With a Mentor Commented:
Here is some info on what you should look for to make sure you removed all:

once done uninstall the NICs in safe mode and let them be rediscovered on reboot, set IP options as usual

is the gateway messed up or something?
Here are the 3 tools that removes Winantivirus and they're free.
Some scanners only remove the bad files and leave bed registry entries modified by the trojan. Use vundofix or Combofix to reset modified reg entries.

1. RogueRemover

2.  Please download VundoFix.exe to your desktop.
* Double-click VundoFix.exe to run it.
* Click the "Scan for Vundo" button.
* Once it's done scanning, click the "Remove Vundo" button.
* You will receive a prompt asking if you want to remove the files, click YES
* Once you click yes, your desktop will go blank as it starts removing Vundo.
* When completed, it will prompt that it will reboot your computer, click OK.
* Please post the contents of C:\vundofix.txt.

Note: It is possible that VundoFix encounters a file it could not remove.
In this case, VundoFix will run on reboot, simply follow the above
instructions starting from "Click the Scan for Vundo button." when
VundoFix appears at reboot.

3. Download ComboFix to your Desktop, from either of these locations:

Double click "combofix.exe" and follow the prompts.
When finished, it shall produce a log for you.
Post that log and a HiJackthis log in your next reply

Note: Do not mouseclick combofix's window while its running. That may cause it to stall
An old trick for Microsoft desktop was to regedit erase dhcp and all subkeys. This is its memory (of 'proper' servers etc), we do like a reformat of that. The next step of rebooting should restore the keys to proper (prior?) condition. DHCP server then getting found based upon response(s) to broadcast RFI, request for information. While multiple servers may yet respond, it is the ones used by asker that will respond first, and be selected ad the one favored more, more based on proximity than by human intervention. Closest one wins.
neat, did not know that. cheers
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