The new version runs, so it is not Mach and not the hardware now. It MIGHT have been a transient hardware problem, but unlikely. It MIGHT have been a faulty program, but also unlikely as as saving it under a different name made it work.
It MIGHT have been ... a bad block on the disk.
You renamed the file and saved it as something else: that would have written it to somewhere else on the disk. Can I suggest running CheckDisk or equivalent?
Cheers
Roger