I have installed Win 7 on a 2nd partition of the same drive that my XP system is on. Dual Boot asks which OS to boot appropriately. When I joined my domain under Win 7, eveyrthing worked fine. Rebooted a number of times back into Win 7 without any problem. However, when I booted up in XP, I was denied access to the network because the PC could not contact the DC. The fix was to remove my XP system from the domain and then rejoin. Now XP worked great...but Win 7 wouldn't work now, for the same reason as on the XP side. When I removed the Win 7 system from the network then rejoined, it now worked great, but the problem was back with XP. I can only surmise from this that the Computer Account that is created for my system in AD is changed by each OS when it registers the computer with the domain in the first place. On both OS's I am using the same PC name, CVCMS115, as well as an LAA of my choosing. Because of this, I can get the same IP address assignment from DHCP. That's important for me since I am an administrator of the network and my PC gets routed to the Internet different than the rest of the network, all based on my IP Address.Is there something that I've missed here? I've seen nothing in all the research I have done about an issue of this sort.

Do you also manage the network switches? It could be that port security is in effect. See this for more. http://articles.techrepublic.com.com/5100-10878_11-6123047.htmlMCSE, MCSA, MCDST [If this post helps to resolve your issue, please click the "Mark as Answer" or "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.]

First of all you may read this article. Do not disk duplicate installed versions of Windows Now we know that every system has their unique SID. If you use the same name in AD, when logon the SIDs would not match although the computer name matches. Therefore the logon will be failed. I suggest you change one of the names and add the both systems into AD. Please note that using different computer names will not change the IP address that is assigned by DHCP, because the records are based on the MAC addresses of your network adapters.Arthur Xie - MSFT

Sorry to be so late in replying guys....haven't had a chance to even work with my installation of Win 7 as of yet. Real Bummer....thanks for the reply cdobbs. I am the network administrator, but I have not implemented port security at this time.I actually implemented Arthur's idea and that took care of the logon problem.Thanks for the info...

Thanks Arthur....should have seen this one by myself. Never even thought about the SIDs in this case. Serious oversite on my part :-)Although I would really like to maintain the same name, I added a single character to the name I use under XP, to the Win 7 installation. Joined the domain and logged on just fine.I appreciate your help here sir, as well as everyone else!Thanks...Eric