Hood,
dashed home at lunch and tried what you suggested, there was no *set files in the Mach 3 folder, I reloaded Mach 3 from disc and it opened up alright, will it have kept all thee settings, I didn't have time to test it.
I will have to run it tonight to check it out.
Does this sort of think just happen? should I keep a backup of the *set files somewhere else on the machine in case?
thanks for the steer.