I've encountered an 'anomaly' in certain versions of 9i that manifests itself as such.......

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connect sys@sid_name as sysdba

gives you an unexpected error

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Try

At command prompt - SET ORACLE_SID=SID_NAME

Where SID_NAME is the instance identifier

Then SQLPLUS /NOLOG
Then CONNECT SYS AS SYSDBA

You never know, it might just work goddamit!!