database in recovery mode

Hello all!

Postgres says that it is in recovery mode.

The log tells me:
-----------------
Oct 30 02:21:32 daisy postgres[1122213]: [197] NOTICE:
RegisterSharedInvalid: SI buffer overflow
Oct 30 02:21:32 daisy postgres[1122213]: [197] NOTICE:
RegisterSharedInvalid: SI buffer overflow
Oct 30 02:21:32 daisy postgres[1122213]: [198] NOTICE:
InvalidateSharedInvalid: cache state reset
Oct 30 02:21:32 daisy postgres[1122213]: [198] NOTICE:
InvalidateSharedInvalid: cache state reset
Oct 30 02:21:43 daisy postgres[1239847]: [251074] NOTICE:
InvalidateSharedInvalid: cache state reset
....

My version is:
--------------
select version();
version
---------------------------------------------------------------
PostgreSQL 7.1.1 on alphaev67-dec-osf5.1, compiled by cc -std
(1 row)

I see two postmaster's:
-----------------------
ps ax | grep postmaster
1182880 ?? T 0:00.02 /Postgres/pgsql/bin/postmaster -D
/Postgres/pgsql/data -B 10000 -d 2 -i -s
1239853 ?? I 2:50.90 /Postgres/pgsql/bin/postmaster -D
/Postgres/pgsql/data -B 10000 -d 2 -i -s

And there is no way to stop postgres:
-------------------------------------
>su - postgres -c '/Postgres/pgsql/bin/pg_ctl -w -D
/Postgres/pgsql/data -m fast stop'
waiting for postmaster to shut
down................................................................ failed
pg_ctl: postmaster does not shut down

The only possibility was to kill postmaster britally by 'kill -9'

Can somebody explain what may be wrong
corrupted memory?

Regards
Reiner