Fstab Corrupt

i have a strange issue on my centos 5, the fstab get corrupt, we have reinstall the OS and with the server empty it get corrupt again, the same problem on a second server, seem that is add /dev/shm line, like this one:

LABEL=/ / ext3 tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0,usrquota 1 1
devpts /dev/pts devpts gid=5,mode=620 0 0
tmpfs /dev/shm tmpfs tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0 0 0
LABEL=/home1 /home ext3 tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0,usrquota 1 2
proc /proc proc tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0 0 0
sysfs /sys sysfs tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0 0 0
LABEL=/tmp1 /tmp ext3 rw,noexec,nosuid,nodev 1 2
LABEL=/usr /usr ext3 tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0,usrquota 1 2
LABEL=/var /var ext3 tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0,usrquota 1 2
LABEL=SWAP-sda5 swap swap tmpfs /dev/shm tmpfs rw,noexec,nosuid,nodev 0 0 0 0
/tmp /var/tmp ext3 /tmp /var/tmp ext3 rw,noexec,nosuid,nodev,bind 0 0 0 0