This message generally means that the "read only" flag is set on the file. This often happens if the file is on a CD, or has been copied off a CD. Files on a CD cannot be edited. Files copied off a CD can be edited/overwritten, but not all programs support the facility. If the program you are using does not allow it, just save the file with a different name. Then you can use the OS to rename or delete the old file and rename the new file. How you do that depends on the OS.