Been quite busy with this thing trying to sort out the problem. I posted to the Norton forums where I am a member and had quite a bit of help there. A Symantec employee came on and said they will look into what you mentioned as a possible cause, and that one of the dump files pointed to one of my dieo drivers. One thing I did was download and update my Bios drivers which were well out of date and touch wood, I haven't had a BSOD since! Ran a Ram test and they were showing ok. Ran also CCleaner and got rid of loads, haven't used one of those for ages. I will come back if I have a further issue with this but for now I think it might be sorted. (Touch wood).