I´ve checked the card on the PC, via fsck and via badblocks.
All seems to be in good shape.
sudo badblocks -sv /dev/mmcblk0p1 -o mmcblk0p1.log
Checking blocks 0 to 94207
Checking for bad blocks (read-only test): done
Pass completed, 0 bad blocks found. (0/0/0 errors)
I´ve used a quality SanDisk Exreme. It´s not even 3 months old. I am pretty sure it´s not the reason for the crash.