red hat will not boot - error 13

[Douglas Ferber]

I got this following error while attempting to boot Red Hat on xenserver (redhat is the guest)
Filesystem type is ext2fs, partition type 0x83
kernel /vmlinuz-2.6.18-128.1.10.el5.xs5.5.0.51xen ro root=/dev/VolGroup00/LogVol00 console=xvc0 rhgb quiet
error 13: Invalid or unsupported executable format

Press any key to continue...


what kind of steps do i need to perform to get this issue resolved? any help would be greatly appreciated