If you use CCleaner, I do not recommend using the Registry cleaner feature of CCleaner, particularly if your Windows OS is 64-bit. There are CCleaner users that do use the Registry cleaner feature and like it. Personally, I've tested it and have seen some registry keys that should not be removed. On the other hand, I use CCleaner's "Cleaner" feature several times a day on both Windows 7 32-bit and 64-bit and consider it an integral tool for maintaining maximum system performance.
Personally, I use jv16 PT 2011's registry cleaner component in the "most aggressive" mode on both Windows 7 32-bit and 64-bit. HOWEVER, I do not recommend the "most aggressive" state for a normal computer user. I recommend that it be set/left at the Default state unless you are pretty computer savvy and continuously watch closely what the more aggressive settings yield to be removed from the registry.
JMO:
Registry cleaners, like security programs, yield false positives from time to time depending on a user's software/hardware configuration. Therefore, any registry cleaning program should used with "cautious eye". JV16 incorporates a significant amount of safety features to enhance its accurracy when determining what registry items can safely be removed. And Jouni has expended major effort to ensure that jv16 PT 2011 works reliably on Windows 7 32-bit and 64-bit. That said, it still can yield a mistake (as will any registry cleaner program) because of the thousands and thousands of different software/hardware variations used globally.
