That happened to me a couple months ago with my Fuji camera. The solution was to copy the photos off (when it lets you), then reformat the card. I popped the card into my computer's memory card reader, right-clicked the drive, and told it to format. If you don't have a memory card reader your camera should be able to do this, though you'll need to consult your manual. (I don't know the steps for that model.) If that doesn't work, my next attempt would be to reinstall the camera software.

Hope this helps,
John