Seg fault in postgres 7.4.7?

My postgres 7.4.7 installation crashed on its own today -- here is the
error log:

ERROR:  duplicate key violates unique constraint "toolbar_pkey"
LOG:  server process (PID 22753) was terminated by signal 11
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.

Is this a known bug?

Akash