Did you find a solution to this problem?
There are several additional troubleshooting items to check for the problems of "memory Card locked" or "memory card error". Not sure if they'll permit me to share this related link. But the link outlines the additional steps to take in a recommended progression to minimize risk of damage to the camera
t00nz aka CR
I had this problem with a Canon SD550 camera when I put a 4 GB card in it. Now I think I know the problem. The camera is not designed to handle a card larger than 2 GB. Larger than that and you get the error message.
I have faced similar problem, in order to fix this error I formatted the memory card afterwards to restore the damaged photos I used macbook photo recovery application. It helped me to restore all the photos safely. You can try it !!!!!!!!!!