PostgreSQL 7.0 problem (may be bug?)

Hello

Consider two simple tables: AA, BB.

proba=# \d aa          Table "aa"Attribute |  Type   | Modifier 
-----------+---------+----------id        | bigint  | val       | integer | 

proba=# select * from aa;id | val 
----+----- 1 |   1 2 |   2 2 |   2 3 |   3 3 |   3 3 |   3
(6 rows)

proba=# \d bb          Table "bb"Attribute |  Type   | Modifier 
-----------+---------+----------id        | integer | val       | bigint  | occured   | bigint  | 

proba=# insert into bb select id,val,count(val) from aa group by id,val;
pqReadData() -- backend closed the channel unexpectedly.This probably means the backend terminated abnormallybefore or
whileprocessing the request.
 
The connection to the server was lost. Attempting reset: Failed.
!# 

After that postmaster sould be rerun.

What is wrong ?
Would you mind to tell me how can I fix the situation.
Using PostgreSQL 7.0, Slackware 7.0.

I can give you the similar example on the same subject.
Again, two tables: CLICK, OTCHET_BROWS.
proba=# \d click                                    Table "click"Attribute  |   Type    |
Modifier                           
 
------------+-----------+---------------------------------------------------------------id_visitor | bigint    | ip
   | inet      | browser    | integer   | referer    | integer   | date       | timestamp | not null default 'Fri Jul
2021:36:05 2001 EEST'::"timestamp"
 

proba=# select id_visitor, browser, count(browser) from click group by id_visitor,browser;id_visitor | browser | count

------------+---------+-------         1 |       1 |    20         1 |       2 |    17         1 |       3 |     2
  3 |       2 |     1
 
(4 rows)

proba=# insert into otchet_brows  select id_visitor, browser, count(browser) from click group by id_visitor,browser;
INSERT 0 6
proba=# select * from otchet_brows;id_visitor | browser | value |             date              
------------+---------+-------+-------------------------------         1 |       1 |     2 | Mon Jul 23 17:04:53 2001
EEST        1 |       2 |     4 | Mon Jul 23 17:04:53 2001 EEST         1 |       1 |    18 | Mon Jul 23 17:04:53 2001
EEST        1 |       2 |    13 | Mon Jul 23 17:04:53 2001 EEST         1 |       3 |     2 | Mon Jul 23 17:04:53 2001
EEST        3 |       2 |     1 | Mon Jul 23 17:04:53 2001 EEST
 
(6 rows)

proba=# 

What is the reason ?

Thanks in advance.

-- 
Vladimir Zolotych                         gsmith@eurocom.od.ua