Nothing, actually the DB was in used by some of my client.
and then they complain that they cannot access it any more..so when checking we see that the service is down; and trying to put it on, we have this error message....after sqlplus no log command. AND any oracle command that is issue return this error message.
The only time I've seen this error is when I've upgraded a 32bit Oracle instance using a 64bit patchset (always remember to inquire about such things when new to a worksite....). Has anyone attempted to upgrade the Oracle binaries on this system when nobody was looking?