What does it mean?

voip=> select * from billing;
Backend message type 0x44 arrived while idle
Backend message type 0x44 arrived while idle
We have lost the connection to the backend, so further processing is
impossible.  Terminating.

select vendor_ip, sum(duration) as sumdur from billing where( call_type = 'E'
and (stime >= 935092800 AND stime < 935179200)) group by vendor_ip;
pqReadData() -- backend closed the channel unexpectedly.       This probably means the backend terminated abnormally
  before or while processing the request.
 
We have lost the connection to the backend, so further processing is
impossible.  Terminating.

Postgres 6.5.1 release, freebsd 2.2.5

---
Dmitry Samersoff, dms@wplus.net, ICQ:3161705
http://devnull.wplus.net
* There will come soft rains ...