Optio 330 Memory Card - This Card Not Formatted Error

I've had this error as stated in the subject line twice. Once, with the original memory card and now with a 128 MB card. The original card worked for a while and then for some reason gave me this error. I tried using the card in a camera store with another camera and it worked. I knew there was nothing wrong with that card. I changed to a higher storage card and that worked for a while and then alas the same problem. Has anyone had this problem or does anyone know how to resolve this issue without having to change the card once more?

Thank you in advance.

Erol