OK. When you normally re-start your sidebar gadgets will normally appear (with black square?) If not you may need to start them manually. As in, you've never used a sidebar gadget before and thought it was time to try them out. I've personally f**rd about with my system that much I couldn't tell you the original path. Maybe in the Control Panel. Now I've said that, whenever I've had gadget issues, once that reg key is deleted, because they (gadgets) were running, they started up properly.
Sorry, yes. Save it then delete! Go For It!