Help on Crashing Server

Hi, I've been using postgresql 6.3.2 with Apache Modperl Eperl for quite
some time without any problems whatesoever. These few days however, the
postmaster seems to die and the web site is unaccessible until I manually
restart it.

I would like to know why and when it died. Can anyone tell me any known
problems? Buggy codes to look out for etc? And where does postgresql keep
its logs

Any remedies?

Please help as it's urgent.

Thanks

Martin