CentOS自动升级问题

CentOS的yum-updatesd服务是可以自动更新系统的，只用稍微调整配置文件/etc/yum/yum-updatesd.conf：
[main]
# how often to check for new updates (in seconds)
run_interval = 3600# how often to allow checking on request (in seconds)
updaterefresh = 600
# how to send notifications (valid: dbus, email, syslog)
#emit_via = dbus
emit_via = email
email_from = yum-updatesd@MO01H36
email_to = caoyuwei@xxxx.com
# should we listen via dbus to give out update information/check for
# new updates
dbus_listener = yes
# automatically install updates
do_update = yes
# automatically download updates
do_download = yes
# automatically download deps of updates
do_download_deps = yes

但是最近发生一件怪事儿，由到了许多邮件，内容大致如下：

Hi,
This is the automatic update system on MO01H36.There was a problem updating the system. The following error message was reported:Failed to build transaction: Missing Dependency: /usr/lib/python2.4 is needed by package libxml2-python-2.6.26-2.1.2.7.i386 (installed)
Missing Dependency: /usr/lib/python2.4 is needed by package gamin-python-0.1.7-8.el5.i386 (installed)
If the problem persists, manual intervention may be required.
Thank You,
Your Computer

最终解决方法是：yum clean all
然后便可以 yum update了，yum-updated也会自动更新系统。
感慨一下团队的力量。这个解决办法是神仙发现的，哈，我们总是能遇到这样的惊喜！
PS: 2010-5-14
阅读CentOS 5.4发行说明的时候发现：

CentOS 5.4 包含了 glibc 及内核的更新。通过 yum 来更新的推荐程序是：

yum clean all

yum update glibc\*

yum update yum\* rpm\* python\*

yum clean all

yum update

shutdown -r now

升级是讲求顺序的.