How to close dead connections immediately

My ODBC client uses single connection to Postgres 8.1.3 server in W2K
In case of TCP error it closes connection and re-opens it.

Unfortunately, in server status window I see a number of connections from
same IP address.

In log file I have lines like

2006-04-24 01:24:41 oksana 188.16.34.194 idleLOG: could not receive data
from client: No connection could be made because the target machine actively
refused it.
2006-04-24 01:24:41 oksana 188.16.34.194 idleLOG: unexpected EOF on client
connection
2006-04-24 01:24:41 oksana 188.16.34.194 idleLOG: disconnection: session
time: 6:19:20.54 user=oksana database=mydb host=188.16.34.194 port=33625

This occurs in 1:24 in midnight while user has exited my application a
number of hours ago.

How to prevent dead connections ?
My server and client are in Windows and TCP_KEEPALIVE parameters have
default settings.

Is it possible to force postgres to close dead connections immediately, not
after 6 hours ?

Andrus.