I do not use the Norton registry cleaner, but use two others religiously. Also every month or so I have it defragmented. I have been using principally Glary Utilities freeware version and never a problem. I never have had a problem. Long ago, maybe it was Norton, I cannot recall, a needed registry6 entry was being deleted. In this case you can put this key in an EXCLUDE list.
But listen, if you do not clean your registry every so often, particularly wihen you have installed new software, you are going to have problems with your computer. SO I STRONGLY RECOMMEND YOU USE A REGISTRY CLEANER FROM A GOOD VENDOR. As I said, you do not have to use Norton. There are other freeware cleaners that are excellent.