I am also getting the GRUB "Error 28" with Red Hat 8.0, although I have an MSI nForce board. The bios is fairly recent, I flashed it about a month ago. How do you solve this problem?
UPDATE: I reinstalled and have the same problem. This time I made a boot floppy, and fortunately that works for booting. But booting off the floppy sucks!. I did a little googling on this issue and found a post where a Caldera tech tells a beta tester (who has an Asus nForce board) that GRUB is the problem. Caldera released a new GRUB that fixes the problem - hopefully Red Hat will, too. BTW, I am using BIOS version 2.6 on my MSI K7N420 Pro.