"No memory space"

Question

I have a Sony Cyber-shot DCS-S50 2.1 digital camera. I have been using it for a while now with no problem and all of a sudden "No memory space" began flashing on my screen. I deleted all of the photos on my camera to make room for new ones but I still get the message "No memory space". I can't take any still photos at all. Any ideas how to fix this without buying a new memory stick? Thanks, Alaska