I uninstalled/re_installed, but still got the same problem. I set the database name as "sugar". The file ORACLE_BASE/admin/sugar/create/seed.log shows:

ORA-03113: end-of-file on communication channel
create controlfile reuse set database "sugar"
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ORA-03114: not connected to ORACLE
alter database "sugar" open resetlogs
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ORA-03114: not connected to ORACLE
alter system enable restricted session
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ORA-03114: not connected to ORACLE
alter database "sugar" character set US7ASCII
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ORA-03114: not connected to ORACLE
alter database "sugar" national character set US7ASCII
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ORA-03114: not connected to ORACLE
alter database rename global_name to "sugar.SalesCentrix.com"
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ORA-03114: not connected to ORACLE
ORA-01012: not logged on