Error loading file (Iso/cso) File corrupt. Help.

[LunaMoo]

Data corruption is pretty common sign of any storage device kicking the bucket. Even if it's new it could simply be faulty. Your mobile itself could also have some kind of other problem like doesn't support sd cards above some size properly and going over some limit corrupts the data on it or maybe the battery is old and doesn't keep stable voltage or something alike, even overheating caused by constant write of data as I imagine copying some large isos would be - could lead to a temporary problem. So you're either very unlucky or simply abused your device a bit too much recently. You'll probably have to format your sd card to repair it's file system if it's not permanently broken.

Nothing of that could be caused by ppsspp as it only reads those files, never modify or move in any way.