Hey, so I have a really strange memory from when gen 4 first came out, but I'm not sure is it's accurate or not.
I remember I used to be OBSESSED with the idea of "hacking" my game, so I purposely tried to break/corrupt it. And I succeeded.
In Heartgold, it said something about my save being corrupted, and it sent me back to a few saves ago. I remember this specifically because I was really sad I lost all my progress and stopped playing for a while. When I played again, I remembered it, and I since just remembered it.
The thing is, human memory isn't reliable. It gave me an error message, but who knows what it actually said. What happens when a gen 4 game save file gets corrupted?