ssh / keyless login problem

Yesterday 10:19:28

I should add that the ssh / system on the remote host is:

ssh -ver
OpenSSH_3.6.1p2, SSH protocols 1.5/2.0, OpenSSL 0x0090701f
uname -a
Linux diesel.eee.nottingham.ac.uk 2.6.5-1.358 #1 Sat May 8 09:04:50 EDT 2004 
i686 athlon i386 GNU/Linux


Dear List,

I am using rsync to backup my local host to a remote host over ssh.  I use an 
empty passphrase key pair so that my scripts can run automatically. I am 
using the scripts and setup described here, "http://www.jdmz.net/ssh/";.

I have a strange problem:

The first time the script runs after a long delay (ie overnight when the local 
host is turned off) ssh always asks for a password despite there being a 
valid key pair on both hosts.  If I kill the script and run it again then it 
runs without asking for a password (as it should).  My script needs to log in 
several times and run automatically so password free operation is essential.

I can't see why the first time fails - my only thought is that the remote 
machine mounts my home directory over NFS and maybe this causes a problem?

Does anyone have any suggestions as to:

How I might solve this problem?
How I might diagnose it? (it is hard to repeat it more than once a day)
How I might stop ssh from asking for a password and return an error instead? 
(in which case I can get my script to handle this exception with a dummy 
login).

Any other suggestions?

ssh -ver
OpenSSH_3.9p1, OpenSSL 0.9.7a Feb 19 2003
uname -a
Linux valium 2.6.11-1.14_FC3 #1 Thu Apr 7 19:25:50 EDT 2005 x86_64 x86_64 
x86_64 GNU/Linux


Cheers,

SA


End of encapsulated message