Error: "The version of the database is incompatible with the Jet DLL version" when registering an (4336063)

Despite the correct DLLs being linked, when trying to register an Exchange 2003 EDB the following error is given during the replay of the transaction logs in the user interface and the the exchdb.log log file:

Nov 14 17:16:37.406 [0836:2684] 3 Database version: 0x620.b, Log file version: 7.3704.8, ESE engine version: 6.7638.2
Nov 14 17:16:37.406 [0836:2684] 3 Fixing restore map
Nov 14 17:16:37.530 [0836:2684] 5 CExchDB::PrepareBackup replay log files to backup databases JetExternalRestore( szNewSysFilesPath = E:\log_exch\mdbdata\dlghrxfd\, szNewLogFilesPath = E:\log_exch\mdbdata\dlghrxfd\, szBackupLogFilesPath = E:\log_exch\mdbdata\dlghrxfd\, szBaseName = E00, minlog=25634, maxlog=25636 )
Nov 14 17:16:38.544 [0836:2684] 5 JetExternalRestore returns error: 0xFFFFFD99 - hard recovery attempted on a database that wasn't a backup database
Nov 14 17:16:38.544 [0836:2684] 5 SoftRecovery cRowsDBsMap = 2
Nov 14 17:16:38.545 [0836:2684] 5 SoftRecovery for files: E:\edb_exch\priv1.edb and E:\stm_exch\priv1.stm
Nov 14 17:16:38.545 [0836:2684] 1 The version of the database is incompatible with the Jet DLL version.