Active Directory and client profiles

Hi,
Hope I explain this clearly. I’m some what new to AD. I had a windows 2003 DC setup with active directory. The server crashed and active directory was reinstalled. Prior to this happening clientS computers(win. xp) down loaded there profiles from the server. After the crash some clients computers are working fine and others are unable to download there profile from the server. They are able to see there home directories and other mapped drives. Would anyone know the reason for this.
I would appreciate any help on this.
Thank You in advance.