connection problem with postgresql driver 8.03.0100 to postgresql 8.3.0

Hi,

I want to upgrade my postgresql database from version 8.1.x to 8.3.x.
everything is working fine, but the odbc connect.
I compiled postgres odbc driver version 8.03.0100, but when I try to connect
to a 8.3.0 postgres database, then there connection/authentication problems
happen:

isql FIS MyUser MyPassword -v
[28000][unixODBC]Communication error during authentication;
Error while reading from the socket.
[ISQL]ERROR: Could not SQLConnect
dbuser(at)dbhost:~> isql FIS MyDatabase MyDatabase -v
+---------------------------------------+
| Connected! |
| |
| sql-statement |
| help [tablename] |
| quit |
| |
+---------------------------------------+
SQL>

I can only connect to the database by a chance of 1/10. Also when I get
connected, then when I try entering a SQL statement, I get error messages
about not being connected anymore.

and below the postgres log from the tries:

LOG: connection authorized: user=MyUser database=MyDatabase
LOG: unexpected EOF on client connection
LOG: disconnection: session time: 0:00:00.002 user=MyUser
database=MyDatabase
host=192.168.15.106 port=52224
DEBUG: server process (PID 19939) exited with exit code 0
LOG: connection received: host=192.168.15.106 port=52225
DEBUG: forked new backend, pid=19941 socket=6
LOG: connection authorized: user=MyUser database=MyDatabase
LOG: unexpected EOF on client connection
LOG: disconnection: session time: 0:00:00.003 user=MyDatabase
database=MyDatabase
host=192.168.15.106 port=52225
DEBUG: server process (PID 19941) exited with exit code 0
LOG: connection received: host=192.168.15.106 port=52226
DEBUG: forked new backend, pid=19943 socket=6
LOG: connection authorized: user=MyUser database=MyDatabase
LOG: statement:
LOG: statement: select version()
LOG: statement: set DateStyle to 'ISO'
LOG: statement: set geqo to 'OFF'
LOG: statement: set extra_float_digits to 2
LOG: statement: select oid, typbasetype from pg_type where typname = 'lo'
LOG: statement: select pg_client_encoding()
ERROR: synt x error at or near " at character 1
LOG: could not send data to client: Broken pipe
LOG: unexpected EOF on client connection

This is the part of the configuration from my odbc.ini:
[FIS]
Description = PostgreSQL DB
Driver = PostgreSQL
commlog = yes
Database = MyDatabase
Host = localhost
Server = localhost
ServerName = pdtest106.pdtest.intern
Username = MyUser
Password = MyPassword
Port = 5430
Protocol = 6.4
ReadOnly = No
RowVersioning = No
ShowSystemTables = No
ShowOidColumn = No
FakeOidIndex = No
ConnSettings =

Actually, I have no idea, what the protocol version number means. The
version 6.4 was the one I found most of the time in the net. I also tried to
set it to 8.3, and 8.3.0, but with no difference. Any pointer to an
explanation would be great.

when I exchange the odbc driver file, with an older one, odbc drvier version
8.1.2, then I do not have connection/login problems at all.
I'm wondering, whether I will loose functionality that I already had, when I
connect to the postgres 8.3 database with a odbc driver version 8.1.2?

Further, do I can connect to the postgresql 8.3 database using an older odbc
driver, and be able to use all the new features of the 8.3 postgresql
version?
Or will there be chanches that sth. not work anymore, what worked with older
postgres database version?

kind regards
Sebastian