And it's equally amazing what answers some people will give.
My card is also locked. 99% of people who use memory cards know to use the little tab slider to un-protect their cards. That's a little piece of info that's been around since cassette tapes and video tapes, only back then you broke off the tabs. Floppy discs had slider tabs to protect them. Yes, I slid the tab both up and down and it didn't matter where the tab was, my 8 GIG card remains locked. I could add pictures to my card if I inserted the card into my memory reader in the computer. But once I put the card in my camera, it says "Memory Card Error. Card Locked!"
Going to the menu of my camera to unlock it doesn't work either. The screen 'greys out' the main menu where you protect the card so you can't unprotect it.
I am presently formatting the card (which I can't do on my camera, but am doing it through the card reader on the computer). Weird how it will allow me to reformat, yet I can't take a picture with it.
You can also get the memory card locked/protected message if you are trying to use a SDHC card in a camera that does not support High Capacity (HC). High Capacity is any SD card with over 2GB of memory space.
UGH, i'm having the same problem with my 8gb sdhc.
I just bought the powershot sx120is about a month ago with a centron sdhc class 4 8.0 gb memory stick. after about 300 pictures, the card formated itself, i didnt know what the problem was till after about 200 pictures later, the camera started reading memory card error, card locked! i don't want to loose these pictures and i know it isnt a problem with the camera, my other memory sticks work just fine on it. it isnt the little lock slide on the side problem either. and it can't be because it's dirty or anything. is there a way to fix it. i'm going a little crazy here
Switched the "LOCKED" 8GB memory card from the Canon SD300 where it did not work, (even after "unlocking" it with the little gray tab and using tape to secure it) to the Canon SX200IS and it worked fine! The suggestion that it can depend on the camera's capacity was brilliant. Thanks for the help! You saved the day!!!