Thanks but I am familiar with the official procedure. I have tried several games and all work and I can save. Only one game will not work (I think) the one with the corrupted save file, which I will find sooner or later. If I leave everything like this, without adding or deleting files, there should be no problem. Backing up and formatting everything: no way!!!
When I find it, obviously I cannot delete the corrupted save file, but I will have to rename the folder that contains the game, so playing it will create a new save file, with a different name.
Only a psp expert will understand this my sophisticated procedure.
If you read all the massages above you will know the answer. Some clusters are certainly corrupted and the data contained in them unrecoverable/ undeleteable. If I tried, as in the past, to erase files with those symbols it would give me an error, but the erasure attempt would corrupt other sectors and the whole SD card.
I expected this answer, which I have already been given. I repeat that all games I tried work and save (except one that I haven't found yet). I just don't add or delete more games: after all, on 32gb I had less than 100mb free left. Most of all, I was curious to show everyone those strange, darn symbols, which everyone will encounter sooner or later.
You will have to learn it the hard way then.
I have good intentions with getting on your (and other people's) nerves with frequent backup reminding. Not listening to this will have bad consequences at some point.