Some Windows "gurus" including Mark R. of Sysinternals fame, say these cleaners cause more harm than good. I'm confused.

Been using Ray's products since Windows 95, and it was me that caused any problems! (good old Winrescue was the tool) =)

What is the straight talk on registry cleaners...Ray ?

   Most registry cleaners are poorly and quickly written to get in on the registry cleaner craze.  These bad registry cleaners often have good graphics and look sharp but they can cause some real problems with the registry.  They are written by programmers who do not understand the structure of the registry.  Yes, they do usually cause more harm than good.
   RegVac, on the other hand, has been around since the beginning of registry cleaners and improves every year.  It uses hundreds of procedures to check and clean the registry in many different ways.  With the registry being the huge monstrosity that it is, it needs a cleaner like RegVac.  RegVac has even been known to repair problems with software that could not be repaired in any other way.
   Unfortunately, I am a programmer and not a marketer or promoter and so RegVac remains a jewel hidden in the forest of poorly written registry cleaners.
   Here is more information on RegVac - http://superwin.com/regvac.htm