Hi,
That sounds like iolite is having troubles saving the DRS to your selected folder. Have you created a folder somewhere on your system where you have full permissions? e.g. [your home folder]/Documents/my_iolite_folder/DRS.
Once you've done that, make sure that iolite is looking in that folder by selecting it in the Paths section of the iolite's Preferences (in particular the DRS path).
That should get rid of the permissions issue. Let us know how it goes and if the settings issue still persists.
Cheers,
Bence