sparkling:

You might need to start from a fresh reboot to turn the swap off (step 3) if you're using enough memory from running processes.

1) open terminal window
2) become root (there's a FAQ on this, but I don't think it adequately describes the n810 process)
3) turn off swap on the internal MMC (swapoff /media/mmc2/.swap)
4) unmount internal MMC (umount /media/mmc2)
5) run file system check/repair (fsck.vfat -a /dev/mmcblkp01)

With any luck that will actually fix the filesystem error. It didn't for me, but this looks like this might have:

6) fsck.vfat -r -t /dev/mmcblk0p1

Beware that this will very possibly result in some corrupted files. :-/ They were most likely corrupted prior to fixing the file system errors, though.