No crazy magnetic fields, no NMR, no MRI, no nuclear explosions, no supermassive stellar remnants.
The corruption seems purely random. Sometimes I can eject and happily read the memory card. Other times I can open the memory card, but the file won't open. Other times it tells me it has a problem the instant I put it in my computer.
Could it be that the corruption takes place when ejecting the SD card while writing to it?
Niels