RHEL5.5 and 5.6 fail to initialize multipath on EMC Clariion in Active-Active mode

Issue

RHEL5.6 server is unable to enable multipath against an EMC Clariion. In a boot from SAN configuration, this results in the system being completely unable to boot, printing:

Setting up Logical Volume Management:   Found duplicate PV xxxxxxxxx: using /dev/sdb2 not /dev/sda2
  Found duplicate PV xxxxxxxxx: using /dev/sdc2 not /dev/sdb2
  Found duplicate PV xxxxxxxxx: using /dev/sdd2 not /dev/sdc2
  2 logical volume(s) in volume group "VolGroup00" now active
                                                           [  OK  ]
Checking filesystems
/dev/VolGroup00/rootvol: clean, 101947/6619136 files, 880867/6619136 blocks
fsck.ext3: No such file or directory while trying to open /dev/mapper/mpath0p1
/dev/mapper/mpath0p1:
The superblock could not be read or does not describe a correct ext2
filesystem.  If the device is valid and it really contains an ext2
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>

                                                           [FAILED]

*** An error occurred during the file system check.
*** Dropping you to a shell; the system will reboot
*** when you leave the shell.
(or type Control-D to continue):

This issue presents itself on kernel-2.6.18-238.12.1. Multipath works on kernel-2.6.18-155.