If you are feeling adventurous, you can try the instructions given by alex in comment 63, except instead of 'sudo edit /etc/rc6.d/S40umountfs', use the command 'sudo gedit /etc/rc6.d/S40umountfs'.
If you are not feeling adventurous (which is ok), I suspect that one of the Ubuntu updates will take care of this for you.
MattiaBorrelli,
If you are feeling adventurous, you can try the instructions given by alex in comment 63, except instead of 'sudo edit /etc/rc6. d/S40umountfs' , use the command 'sudo gedit /etc/rc6. d/S40umountfs' .
If you are not feeling adventurous (which is ok), I suspect that one of the Ubuntu updates will take care of this for you.