postmaster didnt start after power failure.

hi all,
After a power failure in my PC, postmaster didnt start. Manually
starting it by "/etc/init.d/postgresql start" also didnt help. Finally i traced
the problem to be existance of the postmaster.pid file. After i deleted that
file, postmaster started properly. This happened two times.
I am using RH 7.2 and postgres 7.1.3.
Can anyone clarify on why the pid file is not removed on next bootup?
My system is automated and can run for months together without any manual
interventions. In that case, in an unlikely event of power failure, the system
functioning may become improper.
Can somebody suggest a way out of this, please.

--
regards,
hari
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