Comment 3 for bug 329509

I am having this same problem, and it is very frustrating because grub cannot boot either linux or windows.

For me, this started when I was trying to change my external hard drive (which has linux on it) to be able to boot on any computer.

I tried it on my desktop computer, and it booted successfully--once. After that, I always had this problem.

A few days later I noticed that my SuperGrubDisk flash drive partition started having the same problem--after using it in the same desktop computer.

I think that it's a drive access problem that may be solvable with the help of this link
http://ubuntuforums.org/showthread.php?t=442945
...but I was never able to make it work.

Any help is appreciated.