Every time we get on to the darn thing it crashes. I'd have advised the couple to move all the fonts out of the Font folder and restart. If the problem disappears, then a corrupt font is likely. Even with a clean reinstallation, if the corrupt font is put into the new System Folder, the problems will resume. I should have thought of that.
Corrupted fonts are one of the most dastardly things to diagnose.
Gregory's advice is sound. And now for something completely different. But, I don't think it's a very good idea. So unless you want to buy several hard disks and store one of them offsite, I don't think it's an adequate replacement for Retrospect. For what it's worth, I consider Retrospect one of the greatest computer programs of all time and think it's worth every penny it costs.