problem on psql command

Hi,

I have just installed postgresql and i have the following messages :

postgres@2[postgres]$ createdb testpg
/usr/lib/postgresql/bin/readpgenv: line 2: 
/etc/postgresql/postgresql.env: No such file or directory
CREATE DATABASE
postgres@2[postgres]$ psql testpg
/usr/lib/postgresql/bin/readpgenv: line 2: 
/etc/postgresql/postgresql.env: No such file or directory
Welcome to psql 7.3.4, the PostgreSQL interactive terminal.

Type:  \copyright for distribution terms
       \h for help with SQL commands
       \? for help on internal slash commands
       \g or terminate with semicolon to execute query
       \q to quit

/usr/lib/postgresql/bin/psql: relocation error: 
/usr/lib/postgresql/bin/psql: undefined symbol: PQgetssl

what's the problem ?
Could someone help me please.

Thanks.