server process (PID ) was terminated by signal 29

Hi all,

After upgrading one of our database servers from 8.1.11 on SLES9 to
8.2.6 on CentOS 5.1, it crashed several times with following errors:

LOG:  server process (PID ) was terminated by signal 29
LOG:  terminating any other active server processes
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back
the current transaction and exit, because another server process exited
abnormally and possibly corrupted shared memory.
HINT:  In a moment you should be able to reconnect to the database and
repeat your command.
........

LOG:  all server processes terminated; reinitializing

Does this mean bad hardware, corrupted database or something else?

TIA,
Milen