Grub 0.97 on my RHEL6 machine has thrown this error ever since I upgraded to the 2.6.32-642.6.2.el6.x86_64 kernel. I can boot previously installed versions of the kernel, but any kernel I installed after this will throw this error when grub boots that kernel. grub-install runs cleanly, and the disk is partitioned with just a / partition and a 2GB swap partition. The / partition has plenty of space and fsck runs cleanly.
I'm pretty sure this isn't an issue with grub.conf as I can boot the system on old kernels. Does anyone have any other ideas?