Diona just came to me with the message that she couldn’t write to, or remove files from, her SanDisk USB memory stick on the laptop. So I plugged the stick into the PC I am sitting at right now and behold: the same problem. For a moment I was afraid that the memory stick went to memory stick heaven. But after some searching on the internet I found that re-formatting the bugger sometimes helps.

Since the data from the stick could still be read a backup was made, the stick was unmounted and the following command was given to reformat:

sudo mkfs.vfat /dev/sda1

This wiped the entire contents of the stick, but some short tests proved that it was working again.