"ORA-21561: OID generation failed" when trying to connect to SQL*Plus locally from the server, but w

Hi,

I'm getting the error ORA-21561 when I try to connect to SQL*Plus directly from the server:

[15:07 oracle@myhost:~]$sqlplus system

SQL*Plus: Release 11.2.0.3.0 Production on Thu Jan 9 15:07:06 2014

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Enter password:

ERROR:

ORA-21561: OID generation failed

Enter user-name:

I'm connected to the server with the oracle user. OS is Linux x86_64. 

I have already read the Notes on MOS related to this problem:

Note 744125.1

Note 1335327.1

Note 173249.1

Note 559981.1

They all seem to indicate a problem with the hostname entry missing in the /etc/host file. 

I've checked it, and it's true that the hostname isn't there, BUT, and I insist, it was already the case before, and  the host file on all our other servers don't have any entry for hostname, and the connections work fine.