strange postgresql failure

postgres[666]: [1] LOG: server process (pid 3166) was terminated by
signal 11
postgres[666]: [2] LOG: terminating any other active server processes
postgres[806]: [591-1] WARNING: Message from PostgreSQL backend:
postgres[806]: [591-2] ^IThe Postmaster has informed me that some
other backend
billy postgres[806]: [591-3] ^Idied abnormally and possibly corrupted
shared memory.
billy postgres[806]: [591-4] ^II have rolled back the current
transaction and am
billy postgres[806]: [591-5] ^Igoing to terminate your database system
connection and exit.
billy postgres[806]: [591-6] ^IPlease reconnect to the database system
and repeat your query.

After few seconds all backends were disconnected and postgres restarted.
It didn't help :-( Even reboot didn't help...

Postgres is 7.3.2-2 on Debian Woody.

Regards,
Tomasz Myrta