Sorry DerekQ for my delay in responding. No I have not done a recovery but took the next closest step by booting to linux off the cdrom. Unfortunately the same problem occurred and typing a text file in linux caused the screen to go blank and the laptop unresponsive. I can only conclude, now more decisively, that there is a hardware problem. I will have to remove personal files, and Office etc prior to having it looked at.
I really do appreciate your help and guidance yesterday. Many thanks.
cheers
SJ60