Hallo Everyone,

After a lot of fishing around I found this bug-report which describes my problem perfectly: Low-speed, high-CPU-activity, fan permanently running ...

https://bugs.launchpad.net/ubuntu/+s...ux/+bug/280202

The solution they recommend (and which seemed to work for a good number of people) is to switch apic off.

http://ubuntuforums.org/showthread.php?t=1376547

I changed this line in GRUB ...

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash apic=off noapic nolapic"

Which fixed the problem.

Here I am a bit bemused that the initial install was correct but somehow the update messed up by the system update meaning that the problem needed to be fixed with this change to GRUB.

Anyway, I hope these comments help someone out.

Regards,
Alan