[Centos] yum configuration files lost while/after updating ?

Hello centOS users,

Today i've installed a fresh centos 3.1, and modified the [update]
section of my/etc/yum.conf, to point on my own update repository.

My update repository (3.1) contains exactly the same content that the
official one. Update was successful but now /etc/yum.conf is missing :(

Here it is what i've noticed during the update process:

# cat /etc/redhat-release 
CentOS release 3.1 (final)

#yum update

[...]
warning: /etc/yum.conf created as /etc/yum.conf.rpmnew
yum 100 % done 96/191 
[...]
warning: /etc/centos-base-yum.conf saved as
/etc/centos-base-yum.conf.rpmsave Completing update for yum  - 110/191
[...]
Transaction(s) Complete

# cat /etc/redhat-release 
CentOS release 3.3 (final)

=> files /etc/yum.conf*
/etc/yum.conf -> /etc/centos-base-yum.conf ( Broken link! read the
rest)
/etc/yum.conf.rpmnew
/etc/yum.conf-SAVE

=> files /etc/centos*

/etc/centos-base-yum.conf.rpmsave
/etc/centos-yum.conf

I don't understand what happened :-O
An idea ?

-- 
Martin