I recently bought a olympus SP-500UZ and took a few photos when putting them on computer im getting an ERROR?

Hi i recently bought a second hand olympus camera it had a 256mb card in it i took a few photos on it and went to put then on computer with the usb attached and it came up alot of stuff i just said yes now it says card error every time i put the card back in my camera i don't no what to do please help