Using SSPI to connect to remote PostgreSQL server using Npgsql - postgresql

Question

I am using nHibernate + Npgsql to connect to PostgreSQL server using windows authentication (SSPI). I have added the windows user to the Postgres and have configured the settings as recommended by http://wiki.postgresql.org/wiki/Configuring_for_single_sign-on_using_SSPI_on_Windows.
Here is my connection string:
"Server=;Port=5432;Database=;Integrated Security=true"
This is my code:
if (!sessionFactories.TryGetValue(sessionFactoryConfigPath, out sessionFactory))
{
Configuration cfg = new Configuration();
if (sessionFactoryConfigPath != DefaultConfigFile)
{
//Check.Require(File.Exists(sessionFactoryConfigPath),
// "The config file at '" + sessionFactoryConfigPath + "' could not be found");
cfg.Configure(sessionFactoryConfigPath);
}
else
{
cfg.Configure();
}
// Now that we have our Configuration object, create a new SessionFactory
sessionFactory = cfg.BuildSessionFactory();
When I run this I get the following error at sessionFactory = cfg.BuildSessionFactory();
"FATAL: XX000: could not accept SSPI security context"
When I checked the PostgreSQL logs the following entry was found:
"The token supplied to the function is invalid (80090308)"
I am using "PostgreSQL 9.3.2, compiled by Visual C++ build 1600, 32-bit". I got it from postgres website. I am using Windows 7 SP1 64-bit.
What am I missing here? Please help.