ORA-600  [a] [b] [c] [d] [e]
Internal error 4400 means that we are trying to delete a transaction (for
example at logoff time) but the transaction has not yet been marked
This can happen at the remote site in a distributed transaction if the
first part of the first stage of a two phase commit gets an error before
it really starts the protocol.
PROCESS FAILURE - but only at logoff so minimal impact
NON CORRUPTIVE - No underlying data corruption.