OK so I got the PFN_LIST_CORRUPT Blue screen again, rebooted and got this one! that is after the Dell engineer replaced my motherboard and RAM, well supposedly replaced my RAM.... took the suspect stick out and funnily enough my PC boots up OK 
so who knows did he or didn't he replace my RAM???
From looking around at some forums and googling the error a lot of people point it to a driver issue. however in my case I do not think so.
A lot of time a blue screen can be fixed by booting into safe mode and uninstalling drivers etc... however if it blue-screens going into safe mode then you can be pretty sure that it is not a driver issue. The only time I have had that problem is on a Dell Precision Workstation 370 where the RAID config wasn't right in the BIOS, set to AHCI as opposed to SATA, a simple change in the BIOS fixes the problem.
