Computer name has changed

Re-register the computer with the domain using NETDOM. Directions for accomplishing this are available at http://support.microsoft.com/default.aspx?scid=kb;en-us;266651

the event log on the DC or on the local machine or both? what's the event id?

Thanks for your answers. Both the DC and the computer sees it with the new name.
I see many events related to that machine..529,672,680.

Thanks.

in the past i've seen some really really interesting stuff like that and the root cause was the last known good configuration feature having problems overwriting certain parts of the registry. even if that's not the cause, removing the machine from the domain and adding it back should take care of the issue.

I would disconnect this computer from the wall, fast and take a close look at it. If it looks fine after rejoining the network but still gives a wrong name. There is some thing going on that is not the norm. Most computers even after restoring to an older point should still have the same name, unless it came from another part of the company.
Some searching on computers on a network and name being changed but if things are still showing a different name on the computer. Some thing has been done at a admin level or in the registry.
It is just me I am paranoid, I would do a low level format or at least remove all partitions and format the drive and start over with it.

while I agree with the other guys on this, it sounds like it could be another operator trying to get into your network (from that computer) really check hard for hidden operators on that machine. It could be a bug, or a trojen type, or other mal-ware. Or it could be legit (ok, semi-legit) Some software, when installed, sets up it's own account 'administrator' which becomes a 'user' a .Net program for example might do this.

I unplugged the machine the minute I've seen the issue. Now I'm trying to find an answer. Do you have any suggestions of what I should check?

Thanks

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