Starting postgres server on mac os x 10.6.8

I'm having trouble restarting the postgres server on my mac. The error I am getting when I try to run PG is:

could not connect to server: No such file or directory Is the server running locally and accepting connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

Here's the command that I tried:

sudo su postgres

bash-3.2$ /Library/PostgreSQL/9.1/bin/pg_ctl -D /Library/PostgreSQL/9.1/data restart
pg_ctl: PID file "/Library/PostgreSQL/9.1/data/postmaster.pid" does not exist
Is server running?
starting server anyway
server starting

then I checked the server status:

bash-3.2$ /Library/PostgreSQL/9.1/bin/pg_ctl -D /Library/PostgreSQL/9.1/data status
pg_ctl: no server running

I verified that the pg_ctl and pg_conf files were in place.

I then went ahead and tried this:

bash-3.2$ /Library/PostgreSQL/9.1/bin/pg_ctl -D /Library/PostgreSQL/9.1/data start
server starting

then I checked the server status:

bash-3.2$ /Library/PostgreSQL/9.1/bin/pg_ctl -D /Library/PostgreSQL/9.1/data status
pg_ctl: no server running

Why is the postgres not starting? I am doing all this under the postgres superuser, so I should not have any issue with user privileges.

Thanks,

Andrew