TweakNow RegistryCleaner cleans your computer's registry of unneeded registry values to reduce clutter and potentially enhance your computer's overall performance. I've been using this program for several years and it the safest, easiest registry cleaner I've found. I manually check every scan's results and I've never had it identify registry values that could potentially cause a problem if deleted. It identifies registry problems by three levels: Safe to delete, Not fully safe to delete, and Unknown. The safe to delete entries will automatically be checked and can be deleted without problem. For the remaining entries, there is a deep scan mode that will thoroughly scan the registry to fully determine whether the entry is safe to delete or not. Again, I've never had a problem with the deep scan making a mistake. If you feel you've made a mistake, TweakNow automatically makes a backup which can be used to restore any deleted registry values.
TweakNow also offers a paid version containing more features.