HELP With Install 7.4.1 under Cygwin -

I am PostgreSQL newbie attempting to install PostgreSQL 7.4.1 running
under Cygwin on a Windows NT 4.0 SP 6 system.

I am down to the step of initializing the database.

When running initdb in the bash shell, I get the following diagnostics:

$ initdb -D /usr/share/postgresql/data
The files belonging to this database system will be owned by user
"Administrator".
This user must also own the server process.

The database cluster will be initialized with locale C.

fixing permissions on existing directory /usr/share/postgresql/data... ok
creating directory /usr/share/postgresql/data/base... ok
creating directory /usr/share/postgresql/data/global... ok
creating directory /usr/share/postgresql/data/pg_xlog... ok
creating directory /usr/share/postgresql/data/pg_clog... ok
selecting default max_connections... 10
selecting default shared_buffers... 50
creating configuration files... ok
creating template1 database in /usr/share/postgresql/data/base/1...
FATAL: could not create shared memory segment: Function not implemented
DETAIL: Failed system call was s*hmget*(key=1, size=1081344, 03600).

initdb: failed

Any ideas would be appreciated.