Personally i use registry mechanic and have had no problems with it........but then others say to be carefull so ya never know... Not exactly what you wanted to hear but thats my experience with them.
Try this one it's free http://www.ccleaner.com/ I also use Registry Mechanic, never had a problem with either.
JV16 Power Tools is also a Good registry cleaner and Registry Mechanic...These Program have the Option to Back up your registry in case something gets screwed up in your registry so you can restore it..... CHeers