Domain Controller :-) Starting Exchange 2003 installation.
Finally I managed to install my DC, DNS… I stopped this morning at 2 AM and restarted at 7:30 AM. Thanks to Thierry Mille (always of good support) and Tim Hines for his message that solved my issue. Now I start installing Exchange 2003, and hope that I will be successfull. For the moment it goes ok. When it will be finished I will need to reimport my user profile, that will tough, I guess. Thanks to Julia Lerman for her kind message, thats right we are only developers ;-)