User creation error on W2k

I have a DC that was migrated from NT 4.0 to w2k. All my user accounts came over without any problems. Now I have some new accounts I am trying to create, and I create them without a problem, but when the user goes to login, it tells me the account can not be found, or account does not exist. I have tried copying other accounts, renaming older accounts. Nothing seems to work. Any ideas