when I try to use this particular card I get the message "protected card".
From what? The camera itself when you use it? Then the camera or card (newly purchased?) is faulty. And this Q would be better in Camera Forum.
Or from PC when you try to read what's on it? Then it must have some small lockable tab on it.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 19 Meg WBC