It seems that every new gadget needs to get a reset from time to time. I managed to lock myself out of my MDA but there is a way to hard reset it even if you don’t have the password to launch the normal procedure.
To do the reset press the Comm-Manager key as well as the Voice Key and do a reset in the little reset whole (use the stylus). Hold the keys even after you initiated the reset. If the black boot screen pops up press the green phone button.