After upgrading from 11.10 to 12.04, grub is completely broken. There seems to be an issue with the grub of the live image as well (amd64), it will not recognize my keyboard. (works in BIOS and after booting live usb).
I tried purging and reinstalling after chrooting from the live usb. I am able to update my system, but can't set up grub. I get an error message complaining about "unsupported RAID level: 149" What does it mean, there is no RAID set up for this machine? I tried reformatting the boot partition to no avail.
If booting from HD, I get stuck at grub text interface with no keyboard.
Any ideas what to try next?
EDIT: I reinstalled from usb which made my system bootable again, but still many problems. At least some of the problems appear to be related to the nvidia driver, as mentioned here: 12.04 and NVIDIA card problem with NVIDIA Geforce 7025 and removing the nvidia driver (keeping nouveau) seems to work better.
I also found out that the keyboard was set to OS in the BIOS, and setting it to BIOS gave me the keyboard back for the grub menu of the live usb system. Duh.
So many things turn out to be broken I think a clean install will be less of a pain than fixing it all.