kankan 
Your system is in a mess due to inappropriate package upgrades.
Where the troubleshooting/repair process will stop is unsure, as you say you also have php 5 & Mysql 5 installed, and who knows whatever else that is non standard.
Any idea to correct this perl problem ?
You need to look at
/var/log/yum/yum.log
and see what packages including dependencies were updated when you originally ran those commands.
Then you can remove all of them with
rpm -e packagename1 packagename2 packagename3
Then you can download the correct version rpms and install them
Don't use yum as you will just risk upgrading newer incompatible rpms again.
Then for the packages you need to reinstall do
rpm -Uvh packagename1 packagename2 packagename3
followed by
signal-event post-upgrade
signal-event reboot
Note you should really do a major upgrade to sme7.4 with
yum update
signal-event post-upgrade
signal-event reboot
but ONLY do this after you have disabled non standard repos.
Here are the repos configured on my sme 7.4 server
db yum_repositories show
addons=repository
    BaseURL=http://mirror.centos.org/centos/4/addons/$basearch
    EnableGroups=no
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=addons
    Name=CentOS - addons
    Visible=no
    status=disabled
base=repository
    BaseURL=http://mirror.centos.org/centos/4/os/$basearch
    EnableGroups=no
    Exclude=kernel,kernel-smp,mkinitrd,mdadm,initscripts
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=os
    Name=CentOS - os
    Visible=yes
    status=enabled
centosplus=repository
    BaseURL=http://mirror.centos.org/centos/4/centosplus/$basearch
    EnableGroups=no
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=centosplus
    Name=CentOS - centosplus
    Visible=no
    status=disabled
contrib=repository
    BaseURL=http://mirror.centos.org/centos/4/contrib/$basearch
    EnableGroups=no
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=contrib
    Name=CentOS - contrib
    Visible=no
    status=disabled
dag=repository
    BaseURL=http://apt.sw.be/redhat/el4/en/$basearch/dag
    EnableGroups=no
    Exclude=freetype,htop,iptraf,rsync,syslinux
    GPGCheck=yes
    GPGKey=http://dag.wieers.com/packages/RPM-GPG-KEY.dag.txt
    Name=Dag - EL4
    Visible=no
    status=disabled
extras=repository
    BaseURL=http://mirror.centos.org/centos/4/extras/$basearch
    EnableGroups=no
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=extras
    Name=CentOS - extras
    Visible=no
    status=disabled
smeaddons=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smeaddons/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeaddons-7
    Name=SME Server - addons
    Visible=yes
    status=enabled
smecontribs=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smecontribs/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smecontribs-7
    Name=SME Server - contribs
    Visible=no
    status=disabled
smedev=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smedev/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smedev-7
    Name=SME Server - dev
    Visible=no
    status=disabled
smeextras=repository
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeextras-7
    Name=SME Server - extras
    Visible=yes
    status=enabled
smeos=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smeos/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeos-7
    Name=SME Server - os
    Visible=yes
    status=enabled
smetest=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smetest/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smetest-7
    Name=SME Server - test
    Visible=no
    status=disabled
smeupdates=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smeupdates/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeupdates-7
    Name=SME Server - updates
    Visible=yes
    status=enabled
smeupdates-testing=repository
    BaseURL=http://mirror.contribs.org/pub/smeserver/releases/7/smeupdates-testing/$basearch
    EnableGroups=yes
    GPGCheck=yes
    MirrorList=http://distro.ibiblio.org/pub/linux/distributions/smeserver/mirrorlist/smeupdates-testing-7
    Name=SME Server - updates testing
    Visible=yes
    status=disabled
testing=repository
    BaseURL=http://mirror.centos.org/centos/4/testing/$basearch
    EnableGroups=no
    GPGCheck=yes
    Name=CentOS - testing
    Visible=no
    status=disabled
updates=repository
    BaseURL=http://mirror.centos.org/centos/4/updates/$basearch
    EnableGroups=no
    Exclude=kernel,kernel-smp,mkinitrd,mdadm,initscripts
    GPGCheck=yes
    MirrorList=http://mirrorlist.centos.org/?release=$releasever&arch=$basearch&repo=updates
    Name=CentOS - updates
    Visible=yes
    status=enabled
If centosplus is enabled, then you need to do
db yum_repositories setprop centosplus status disabled
Do similar for any other non standard repos you have enabled, then do
signal-event post-upgrade
signal-event reboot
You can check the setting with
db yum_repositories show centosplus
and so on