Getting a fatal connection error in one of the instances and is unable to connect. (4277050)

Getting a fatal connection error in one of the instances and is unable to connect. Errors reported to the console are ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
HP-UX Error: 2: No such file or directory

After placing the agent in debug, the following error message is indicated:

daoCore::pc_oracleConnect(): CONNECT failed : ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
HP-UX Error: 2: No such file or directory

Jun 28 2007 14:42:51 Core(002): SQLError: daoCore::pc_oracleConnect(): CONNECT failed : ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
HP-UX Error: 2: No such file or directory

Jun 28 2007 14:42:51 Core(002): SQLError: offset 0
Jun 28 2007 14:42:51 Core(000): Ora_Connect_Status_371 daoCore::pc_oracleConnect(): CONNECT failed SQLError - ORA-01034: ORACLE not available
ORA-27101: shared memory realm does not exist
HP-UX Error: 2: No such file or directory

Jun 28 2007 14:42:51 Core(002): !!! Default pct is: 0
Jun 28 2007 14:42:51 Core(010): formatConnectCd(-1034,,32)
Jun 28 2007 14:42:51 Core(002): !!! Returning avail pct of: 0
Jun 28 2007 14:42:51 Main(000): Collect returned false !!
Jun 28 2007 14:42:51 Core(015): Not connected to DB - don't do cursor count
Jun 28 2007 14:42:51 Main(010): Do we have a collection to run?