There is a LAN made up of about 20 work stations (XP), one server with Windows 2003 Server installed. There are one domain and three sub-domains set in the newwork, namely, aaa.com, aa.aaa.com, bb.aaa.com, cc.aaa.com. In the server located at the brach where i work, i use the "Active Directory User and Computer" from the administration tools, and can only see the domain aaa.com in which there is no users corresponds to the workstations in my branch's LAN. By setting the permission of of the shared folders on the server, i found all corresponding users in the domain aa.aaa.com. The server in my branch is in the domain aa.aaa.com, and all the work stations are categorized in to three workgroups. I reinstalled my computer due to some software problems, but after that, i was told have no rights to access the server even i have entered the correct username and password. (the username is found in the domain aa.aaa.com) I have tried different formats of username, but still didn't work. (Such as Username, Username@aa.aaa.com, Username@aaa.com, aaaaa\Username ) Then I tried entering the username and password of the server, it works, but failed again when i rebooted the system.
Where is the problem, what should i do to login into the domain and access the server?