invalid data in PID file

Hi,

I'm trying to start my postgres server using

#> pg_ctl start -D /usr/local/pgsql/abc

and get an error like:

invalid data in PID file "/usr/local/pgsql/abc/postmaster.pid"

can anyone comment whats wrong.

My postmaster.pid file is empty at the time when i run this command.

Regards,
Jas