Hi cluberti, Thanks for replying. I hate to be so vague but I've seen various messages and I have been unable to start up for sufficient time to save any of the mini dumps. There seem to be several different messages. They include from memory:- PAGE_NOT_EQUAL IRQ_NOT_EQUAL ACPI.sys and many many more that I can't remember When I try startup repair its reporting Problem Signature 6.0.6001.18000; 6.1.7600.16385; AutoFailover and Corrupt Registry Its blue screening on the XP and Vista boots as well. I think I hoped someone would confirm or deny that this has anything to do with the MS blooper of the Feb security update or if that was just a coincidence. If its not that maybe I need to put the spotlight on my hardware. I had got to desperate measures when I tried to reinstall but even that wiill not work. Brain addled!