I took the PC back to Packard Bell as it still in warranty (just) and in fairness they changed the processor, but with the EXACT same type!
The PC worked OK for around 10 days and now it's started freezing and blue screening again.
Does this sound like the Sandy Bridge problem and if packard Bell changed the processor for the same type would it still have the same problem or would a newer processor of the same type have the problem resolved?
Grateful for any advice as I really need to get this sorted with my exams coming up.
The issue is not related to the processor, it is related to the chipset of the motherboard on your laptop, so changing the processor for the same one or a different one will not matter.
The Intel 6 series chipset issue is related to the SATA ports 3 and higher not working, usually laptop systems do not have more than 2 SATA devices connected, so the issue will not show up, and behavior that you are reporting does not seem to be related to this SATA ports not working properly.
Anyways, in order for you to determine if your system has the SATA ports issue, you need to contact your laptop manufacturer and ask them if the chipset on your laptop system is revision B3 or lower, If it is B3 it does not have the issue, if it is B2 or lower, it will be one of the chipsets with the issue.