A lot of upgrades from ESX 3.0 to ESX 3.01 result in a GRUB message at boot up.

First of all if you have this problem try to remove all the SAN Storage and do the upgrade for a second time. This solution worked on 4 of 5 hosts.

The solution for the last host was a bit more complicated:

	Boot the system with the CD
	Right click on the window and start a Terminal Session-Aterm - Superuser
	mount the root partition in my case: mount /dev/sda3 /mnt If you unsure what device is your root partition use   fdisk -l
	mount /dev/sda1 /mnt/boot