Hi to all of you,
I may have found a solution for those who have a full size keyboard: try to switch the Num Lock off while connected to the remote machine.
To do so, press: shift + clear
The clear button contains a rectangle with a big x con it, on a full size mac keyboard is right above the 7 key on the numeric keypad.
For the owners of a small size keyboard try to google on the internet how to switch off the num lock on your keyboard.
Hope this helps. It worked for me.