I'm having exactly the same problem, Amjad. I have no idea what the problem is. Here's a clue, though, in my server logs:
[01/Sep/2000:16:24:25][5337.1024][-main-] Notice: loading: /home/aol30/bin/postgres.so
[01/Sep/2000:16:24:25][5337.1024][-main-] Warning: could not load /home/aol30/bin/postgres.so: /home/aol30/bin/postgres.so: cannot open shared object file: No such file or directory
[01/Sep/2000:16:24:25][5337.1024][-main-] Error: nsd.db: could not load driver: postgres
[01/Sep/2000:16:24:25][5337.1024][-main-] Error: nsd.db: no such default pool: main
