On 25 January 2015 at 11:44, Brian May <brian@microcomaustralia.com.au> wrote:

I have a i7 based HP computer here that until recently was booting Linux and Windows just fine. According to the user, it stopped working after updating the graphics drivers under Windows.

I finally got it working again.

I was forgetting that you can't (re)install grub-efi unless you are booted using EFI first. As my live boot CD was legacy boot not EFI, that rendered my initial attempts to reinstall grub invalid. (sometimes it will tell you, curiously not after booting from this live CD).

Anyway, I installed the USB image of rEFInd (http://www.rodsbooks.com/refind/) onto a USB device, booted from it using EFI. It immediately found a number of boot options, including my existing grub setup. I booted from this, then selected by installed Linux image. Curiously all this worked.

Once booted, I run as root:

grub-install /dev/sda7

update-grub

Now everything works again[1].

I am still a bit puzzled what happened, maybe the windows update did something to stuff up my grub. At least it is working now.

Thanks for everyone trying to assist.

Notes

[1] Actually memtest still is broken, am suspecting that the images provided with Debian wheezy don't work with EFI.

Brian May <brian@microcomaustralia.com.au>