Question : Can't Add User in Active Directory

I have been trying to add a new user to active directory and keep getting an error that says I should contact the administrator.   I am the administrator and do not know what might be causing this.  I don't believe it is the password as we have a very liberal policy.  What else might prevent me from adding a new user?  We are very low on disk space ... would that be causing the problem?

Answer : Can't Add User in Active Directory

Also one more alternate test, join any other existing user id into the Domain admins group and logon to the DC with that id and test if you can create an User.