AD not abel to copy user acount - The name reference is invalid.

I had 3 servers which are in one domain on separate offices. OS on the servers is WS2003 SP2,and there is no exchange installed on them.
The problem is one of our company left, so there will be other guy which will work on his place. So I took the laptop remove it from the domain, delete the old user account and the old computer account and try to recreate them again with the new user account name. There are two problems 1. If I try to copy any user account from ADUC and rename it its giving me ?Windows cannot create the object (user name) because: The name reference is invalid."
Bear in mind that if I try to creat this new user account by selecting NE user, and filling all data, then its successfully created and appear in ADUC, but when I join this computer to the domain and when its asking me ?please type the name of the user which will use this computer? Im typing the new user account which I create manually the windows 7 (client computer) says "The user account XXX in the domain XXX does not exist. Please check the name and try again". I try with manually IP address and DNS but still not help me. I also try to rename one of the other account with the name of the new user and then to join this PC again but still gives me the same errors.

Any help will be appreciated thanks