Crash on select?

One Beeg Table:

---snip---
/dev/hdc1 6033323 5414189 306672 95% /var/lib/pgsql
---snip---

---snip---
local-mon:/var/lib/pgsql/data/base/corona # ls -l iptraffic*
-rw------- 1 postgres daemon 2147475456 Jun 11 03:16 iptraffic
-rw------- 1 postgres daemon 2147475456 Jun 11 03:16 iptraffic.1
-rw------- 1 postgres daemon 1225385984 Jun 11 08:09 iptraffic.2
---snip---

One Query:

---snip---
select sum(size) from iptraffic where date = '19990601';
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.
---snip---

One `tail /var/log/postgres.log`

---snip---
DEBUG: --Relation pg_indexes--
DEBUG: Pages 0: Changed 0, Reapped 0, Empty 0, New 0; Tup 0: Vac 0, Crash
0, Un
Used 0, MinLen 0, MaxLen 0; Re-using: Free/Avail. Space 0/0;
EndEmpty/Avail. Pag
es 0/0. Elapsed 0/0 sec.
ERROR: parser: parse error at or near "*"
ERROR: parser: parse error at or near "*"
ERROR: parser: parse error at or near """
ERROR: parser: parse error at or near "*"
ERROR: iptraffic: cannot extend
TRAP: Failed Assertion("!((*(&(buf->io_in_progress_lock)) == 0)):", File:
"bufmg
r.c", Line: 656)

!((*(&(buf->io_in_progress_lock)) == 0)) (0)
ERROR: parser: parse error at or near ";"
---

Why the "-" sign?

---snip---
>select sum(size) from iptraffic where date = '19990601';
sum
----------
-393538142
(1 row)
---snip---

Thanks!
ChrisG