What is wrong with my digital camera and/or picture card(s). Camera keeps saying card full.?

Camera-Fuji-FinePix E550 Digital- Card used is FujiFilm. Computer is iMac-Leopard-I have just starting using this camera again after a couple months and for some reason it is telling me that my card is full when I haven't even taken any photos or have any on the card. I changed cards and it worked with a new card for about a day and then did the same thing. Is it a setting on the camera or did I do something wrong with my computer. The only thing I can think of is because it is a Mac you are suppose to drop your device in the trash to eject it otherwise you can damage. I forgot to do that once with the camera and it gave me a warning that damage could have occurred. I have accidently done this before with external flash drives and never had a problem. I don't understand how both of these cards are now damaged. It seems like my camera has a virus. Is this possible? Not sure what to do....HELP