Run dcdiag post results.
Best way to fix is to run the burflag since you still have a functioning 2003 server.
Take backup of the policies and script folders from both the servers from c:\Windows\Sysvol\domain
Stopped NTFRS service on both DCs.
On 2003 server go to this registry key to make this server authoritive:
HKLM\System\CCS\Services\NTFRS\Parameters\CumlativeReplicaSets and Set the Burflags value to D4. This should be done with server which has the Updated information available or correct data.
Went to other DC and made that Non-authoritative by navigating to same registry location HKLM\System\CCS\Services\NTFRS\Parameters\CumlativeReplicaSets and Set the Burflags value to D2.