Forgive me for harping on this but i don't think the current user interface for this function is sufficient.
It's just not at all understandable from using the program what is going on -- either what the function does, or how to undo it. the new checkbox just confuses things more.
It is my opinion that any time you have a function that can make such serious changes to the person's registry, you have a very heavy responsibility to warn them and be careful.
If you release the program as is, you are going to have people posting about how all of a sudden their computers can no longer write their usb drives. and they may only discover this AFTER they have uninstalled and deleted your program!!
I suggest you remove this function completely from your program - maybe make a separate program for changing this registry setting so at least users know what they are getting into.
If you insist on having this function in your program, you need to change the user interface.
Maybe show a message on the screen telling user the CURRENT state of their registry, for example:
"Your registry is currently set to allow ALLOW USB drive writing (normal)" vs "Your registry is currently set to BLOCK usb drive writing completely";
And a BUTTON to change the setting, which says on it "DISABLE ALL USB DRIVE WRITING FOR ALL PROGRAMS" or "RE-ENABLE USB DRIVE WRITING FOR ALL PROGRAMS"
And when the press the button a big bold warning has to come up saying
If you choose to block usb drive writing, your system registry will be changed and will block all usb drive writing by any program. This setting will stay in place even after a reboot, and even if you uninstall this program. To re-enable usb drive writing you need to run this program again and re-enable it."
I'm sorry to be so serious about this but i think you are really asking for trouble and going to have people complaining to you if you leave this function as is.