The only time I have seen this type of issue with the scenario you are describing is when steps were skipped in the upgrade/migration of servers.
There are 4 primary reasons for this problem.
1) DNS/AD was not properly preped.
LOOK FOR = duplicate device by name/ip
SOLUTION = Resolve the conflict on the system by changing the name/ip or update DNS/AD
2) Hardware Re-used
LOOK FOR = duplicate mac/ip
SOLUTION = remove bad cache or introduce new hardware
3) TCP/IP stack has problems.
LOOK FOR = improper TCP/IP behavior
SOLUTION = run the command (netsh ip int reset reset.txt)
4) Proxy ARP Cache
LOOK FOR = {EDIT} someone is broadcasting (like a cisco pix or asa) for arp.
SOLUTION = turn off gratuitous ARP by setting the value of the ARPRetryCount to 0.
Based on information already provided and without any additonal troubleshooting do the following.
1) reset tcp/ip stack (problem 3)
2) check for duplicate mac address' (problem 2)
3) turn off gratuitous arp (problem 4)
4) resolve dns/ad issues (problem 1)
The only exception would be if i knew starting off that DNS/AD was never properly preped I might look at it sooner.
(edit)
if I were to place money on a problem I would pick problem 4 as the most likely.
To save you some confustion here are the steps to do number 4:
1. Click Start , type regedit in the Start Search box, and then press ENTER.
2. Locate the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters
3. On the Edit menu, point to New , and then click DWORD Value .
4. Type ArpRetryCount .
5. Right-click the ArpRetryCount registry entry, and then click Modify .
6. In the Value data box, type 0 , and then click OK .
7. Exit Registry Editor.
(Reboot)
