To prevent my mobile beeing mounted as storage , i put the following line in
/dev/disk/by-uuid/36DF-0070 /media/diamond vfat noauto,nouser,defaults 0 0
Nautilus seems to ignore this and tries to mount the device, which is only prevented by using the
nousers option (a windows appears, the device can only be mounted by root).
It seems to be a known bug but the mentioned workaround doesn't work for me.