Sounds like it's a bad hard drive, which is a fact of life these days. With bigger capasities, it gets worse each day.
Sounds like we all need to go back a few years. My TI-99/4A and TRS-80 Model 100 still work after thirty some years. Talk about reliability. :wink:
Assuming that she has the oldest iMac out there, a Bondi Blue 233/32MB/4GB, it would be just over five years old. I have one of those. Install 9.1 on that thing and it will chug on like a champ. I ran X on that thing since public beta, because it was all that I had. I nuked X and my parents like it again. It's not that X isn't nice, it's just that the UI slows things down if you don't have the hardware acceleration for that. That iMac only had an integrated Rage IIC Pro 2 MB card in it. Good luck with that...... software rendering all the way! :-P