Why do I need a registry cleaner?

[laurentio]

A Free Registry Cleaner will clean up your Registry by finding
Missing Shared Dlls
Unused File Extension
Invalid ActiveX
Invalid Help Files
Invalid Paths
Sound and App Events
Obsolete start menu order
Invalid Fonts
Invalid application paths
Invalid startup programs
Invalid custom controls
Missing Shortcut reference
Obsolete Software Key
Invalid Installer reference
Missing File and Folder