Blank screen

This has happened several times with the GE alarm clock 7-4801. I have it set to go off at a certain time and the alarm to be a CD track. That works and I am half asleep and I push the snooze button and then i don't know what happens but I fall back asleep and then wake up and the whole screen is blank like it's frozen and I have to unplug it for it to be able to set it up again. I'm doing something wrong half asleep in a certain sequence that's causing this and if I knew what i was doing, maybe I would stop. It's made me late for work several times. Thanks.