Files can get damaged over time, for reasons unknown, but it happens. PS one cards (read above). My addition is that I've had lots and lots of trouble with multi internal cards (ones that have 2 x 15 slots or more). They tend to crap out pretty harshly, like my Mad Cats x16 card, my 18 x 15 Memory card (green with to buttons on the bottom, looks like a little game boy), and the 9 slot cards. The dual card is the only one that's worked for all these years.

Then, sometimes you can save over to another PS one card, and it will "recover" the file, but that's a rare chance.