A pg_hba.conf problem - again...

So there is Fedora Core 3 with PostgreSQL 8.1.3 installed from rpms.
The server listens on all interfaces. For testing, I used this
pg_hba.conf (default with added line) and it worked:

local all all trust
host all all 127.0.0.1/32 trust
host all all ::1/128 trust
host all all 10.144.3.0/24 trust

Very happy, I changed trust in the last line to MD5. The application
(pgAdmin) stopped connecting (yes, sql user and its password was
correct). No error, just "unable to connect" or something like this - I
have localised version - in the status line. Is there something wrong
with above file or maybe there are some missing libraries, of which I
(and rpms) am not aware of? :(

Thanks for any suggestions,
Bart Golda