Thanks, Michael; with that hint I tried a google search on "Asus 
Sabertooth FX" + "secure boot" and found a You-tube video showing me how 
to do all sorts of tweaking, including disabling secure boot. Tried 
that, and now I can boot from the rEFInd CD.
Cheers
Ian
--
Ian Park
email: i.d.c.park@???
--
On 08/11/14 21:26, Michael Daffin wrote:
>
> That is secure boot preventing you from booting an unsigned kernel. 
> You should be able to disable it in the BIOS though some don't label 
> it as so obviously.
>
> On 8 Nov 2014 21:18, "Ian Park" <i.d.c.park@??? 
> <mailto:i.d.c.park@ntlworld.com>> wrote:
>
>     I recently bought a new PC from PC Specialist (the third one I've
>     had from them - the laptop I'm using to compose this, and an
>     "entry level" desktop for my wife). The new machine has an Asus
>     Sabretooth motherboard with a UEFI BIOS.
>
>     The first time I booted up the PC, I was too slow to hit the F2
>     key to go into the BIOS, and it booted into Windows (I'd specified
>     that I wanted the machine with no OS, but I guess that PC
>     Specialist installed Windows for the system test). I promptly did
>     a restart, and this time caught it in time to hit F2 and go into
>     the BIOS. I was able to change the boot order so that it booted
>     from the Mint live DVD, stoked up gparted and re-arranged sda to
>     have the partition layout I wanted (sda1 as 512MB for the EFI boot
>     partition, sda2 & sda3 as 20GB partitions for root of Linux Mint
>     and another OS to try out if I fancy it, sda4 as 20GB swap and
>     sda5 as the remaining 160ish GB for the "visible" home partition
>     to share between 2 distros. I was then able to install Mint 17 on
>     sda2.
>
>     I then followed the tutorial in Linux Voice issue 2 to set up sda1
>     as the EFI boot partition and install the rEFInd boot manager. I
>     hit a rock when I tried to boot from a USB stick with rEFInd on
>     it, or a CD with rEFInd on it. The error message was: "The system
>     found unauthorised changes on the firmware, operating system or
>     UEFI drivers." I have a strong suspicion that this was an
>     after-effect of the Windows installation which I deleted.
>
>     Can anyone suggest a way of removing this Windows contamination,
>     please?
>
>     Thanks in advance
>
>     Ian
>     -- 
>     Ian Park
>     email: i.d.c.park@??? <mailto:i.d.c.park@ntlworld.com>
>     --
>
>
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