connection failed in threaded application

I use PostgreSQL 7.1.3 on both Linux 2.4 and Solaris 8 with my multi
threaded application. The application has 16 threads and each thread
opens a connection to PostgreSQL. Under Linux, this works just
fine. Under Solaris, 11 threads succeeds in connecting to the
database, but the rest fails with:

connectDBStart() -- connect() failed: No such file or directory
Is the postmaster running (with -i) at 'localhost'
and accepting connections on TCP/IP port 5432?

I am running postmaster with "-i -N32 -B64" so there should be enough
allowed connections for my application. I have set the systems SHMMAX
to 16MB instead of the default 1MB.

Has anyone seen this happen before, or know why it could happen? The
fact that 11 threads succeeds sounds very strange to me.

Greetings,

Tomas