your computer could not be joined to the domin .you have exceeded the maximum number of computrer accounts your are allowed to create in this domain.contact your system administrator to have this limit reset increased

By default users can only add 10 workstations to the domain without being an administrator.How to allow specific users to add workstations to the domainhttp://networkadminkb.com/kb/Knowledge%20Base/ActiveDirectory/How%20to%20allow%20specific%20users%20to%20add%20workstations%20to%20the%20domain.aspx