I'm afraid that 'Comanche 3' beat me, but then it is a helicopter game, and I never did understand them.
Luckily Tiny provide a 'restore' disc, which puts the computer back into the state that it was in when it was delivered. I now just have to reload my software (but NOT Comanche 3). I can now read PPRuNe in all it's colourful glory.
Many thanks to you all for your advice.
Airclues