10g job scheduler errors

SQL> exec dbms_scheduler.run_job('daily_backup') BEGIN dbms_scheduler.run_job('daily_backup'); END;

*
ERROR at line 1:
ORA-27369: job of type EXECUTABLE failed with exit code: Incorrect function.

ORA-06512: at "SYS.DBMS_ISCHED", line 148
ORA-06512: at "SYS.DBMS_SCHEDULER", line 374
ORA-06512: at line 1

This is a Windows 2000 server. The job was successfully created:

SQL> BEGIN
  2 DBMS_SCHEDULER.CREATE_JOB (

  3     job_name           =>  'daily_backup',
  4     schedule_name      =>  'dave.backup_schedule',
  5     job_type           =>  'executable',
  6     job_action         =>  'C:\OracleScripts\10g\full_backup.bat',
  7     enabled            =>  true,
  8     comments           =>  'Daily full backup');