bug(?) if int8 as primary key

My database (pgsql 6.4.1, linux i386, compiled by egcs-1.1.1) does weird things:
david=> create table t( i int primary key );
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index t_pkey for table t
CREATE
david=> drop table t;
DROP

*** table t doesn't exist

david=> create table t( i int8 primary key );
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index t_pkey for table t
ERROR:  Can't find a default operator class for type 20.

*** exist table t or not ?

david=> create table t( i int primary key );
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index t_pkey for table t
ERROR:  t relation already exists

*** yes!

david=> drop table t;
ERROR:  Relation t Does Not Exist!

*** no!

If I restart pgsql, I can create table t (with int as primary key, not
int8).
        Happy Xmas,                David

--
* David Sauer, student of Czech Technical University
* electronic mail: davids@iol.cz (mime compatible)