Copying rows between two Oracle tables with blob columns fails at some point with an ORA-03127 error.
This is due to an Oracle 8i bug.
The problem is resolved in the latest patches of ArcSDE 9.0 and 9.1 for Oracle 9i Release 2 and up. There is still a problem with earlier versions of Oracle 8i that may be resolved with the latest patches to Oracle 8i. The best solution is to upgrade to the latest version of Oracle 9i Release 2 or higher.