Out of file-descriptors message

Hello All

We are having an issue and it appears to be with file descriptors.
We are running PostgreSQL 7.4.13 on RHEL 3.0 box. This system is running
Redhat Cluster Suite with each system running multiple postmasters. The
error has occurred on both boxes and we can't find any consistencies on
what is causing the problem. I don't see this message in dmesg or any
other log file. It only appears in this single database. There are other
databases running on the same host but from different postmasters and I
don't see the same message. A couple of things to add is that this has
happened on another machine from a different database. When this
problem has been reoccurring for a period of several days the server
get fenced by the other machine. Don't know if related but seems to
happen at the time when the descriptors error is occurring. Here is a
snippet from the log of one of the databases.

2006-11-29 14:57:51 [3823] LOG: out of file descriptors: Too many open
files; release and retry
2006-11-29 14:58:01 [3823] LOG: out of file descriptors: Too many open
files; release and retry
2006-11-29 15:00:26 [3823] LOG: out of file descriptors: Too many open
files; release and retry