Several PostGreSQL questions.

Greetings.

We've recently been seeing several database crashes. The last things seen
in the logs are :

postmaster: StreamConnection: accept: Too many open files in system
postmaster: StreamConnection: accept: Too many open files in system
FATAL 1: ReleaseLruFile: No open files available to be closed
IpcSemaphoreLock: semop failed (Identifier removed) id=512
IpcSemaphoreLock: semop failed (Identifier removed) id=513
(repeated about 20-30 times)
IpcSemaphoreUnlock: semop failed (Invalid argument) id=515

FATAL: s_lock(40014065) at spin.c:127, stuck spinlock. Aborting.

FATAL: s_lock(40014065) at spin.c:127, stuck spinlock. Aborting.

FATAL: s_lock(40014065) at spin.c:127, stuck spinlock. Aborting.
(repeated about 100 times)

This is PostgreSQL v7.0.2 under a Debian 2.2 system with a custom 2.2.17
kernel installed. I have the maximum per-process file descriptor limit set
to 1024, and the maximum system file descriptor limit set to 8192, so I'm
confused about the first messages.

I'm also seeing :

Sorry, too many clients already
Sorry, too many clients already
Sorry, too many clients already

notices, but I thought I increased the number of allowed conncetions.
What's the correct way to go about doing this? :)