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:
Messagefrom 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