Can't change speed camera

For several days, even weeks, I've been having a problem with my camera. I can't change the speed of the camera, whether the game is open or not. When I try to save the changes I've made, I get : "You do not have permission to open this file. Consult the owner of the file or an administrator to obtain authorization". As a result, I'm no longer able to film my machinimas or anything else, and I've searched the Internet to no avail, but there's nothing about this problem.