unexpected EOF on client connection vs 9.0.3

Hello there,

I'm getting regular Postgres log entries with the following error:
2011-03-07 01:00:01 CET LOG:  could not receive data from client: No
connection could be made because the target machine actively refused it.
2011-03-07 01:00:01 CET LOG:  unexpected EOF on client connection

They always appear together.
The server is PostgreSQL 9.0.3, compiled by Visual C++ build 1500,
64-bit running on Windows 2008 R2 SP1 x64, the client is a ASP.NET
application running npgsql.

I've checked and verified that all connections are closed within the
code, what's more, the problem has appeared just as I've moved server
from Fedora Linux x86_64 running Postgres 8.4.2 to the Windows and 9.0.3
(details above) thus I conclude this is not a client problem indeed (the
failure didn't occure on Linux).
The connections are closed from time to time immediatelly as I get
ASP.NET errors.

Thanks for any help in advance.

Piotr Czekalski

P.S. The connection string is:
...Server=127.0.0.1;Port=5432;User Id=<user here>;Password=<password
here>;Database=<database here>;CommandTimeout=360;" providerName="Npgsql"...
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