Problem with amd under RH 5.1

[Stefan Boresch <stefan mdy univie ac at>]

I am just realizing that I am having an intermittent problem
using amd (am-utils) under RH 5.1.  Everything works perfectly for up to
a week, then suddenly amd doesn't understand the NIS maps
any more.  The problem also affects i386, but I
am most concerned about my two Alphas.  For the time being, the
problem can be resolved with 
/etc/rc.d/init.d/amd stop 
followed by
/etc/rc.d/init.d/amd start
but that's only a small consolation.

Any helpful hints appreciated -- I would also be interested if anyone
using a similar setup has no problems!

Technical details:

This is RH 5.1 with all (applicable) patches from the RH errata list
applied; i.e. am-utils-6.0a16-2 and glibc-2.0.7-19
The kernel is 2.0.35, self-compiled from the RH provided sources.

Some output from /var/log/messages once the problem has started:

Aug 17 00:07:02 delta amd[302]: error grabbing nis map of amd.data: Internal NIS error
Aug 17 01:11:02 delta amd[302]: nis_isup: error getting the order of map of amd.people: No more records in map database
Aug 17 01:11:02 delta amd[302]: mapc_sync: map amd.people is down: not clearing map
Aug 17 01:11:02 delta amd[302]: nis_isup: error getting the order of map of amd.
data: No more records in map database
Aug 17 01:11:02 delta amd[302]: mapc_sync: map amd.data is down: not clearing map

However, a ypcat amd.people shows the expected output.

One further detail that may be pertinent: 

Both affected machines have written the following line once to the
console (NOT in dmesg, NOT in /var/log/messages !!!)

get_myaddress: socket: Too many open files