I agree with the excellent advice from TrekDozer regarding registry cleaners and would like to add my opinion that they should not be used, this includes both commercial and freeware versions. Due to these type of program's advertising hype far to many users do not realize the substantial risk involved running such a program. See the below links for more information:
Registry Booster is a registry cleaner designed by Uniblue Software program for windows-based PCs that ensures that the system’s registry is in good situation for higher PC efficiency. This freeware deep scans the registry to establish errors and issues which will trigger slowdown and instability of the PC.
Uniblue Registry Booster Download
Is it advisable to use Uniblue Registry Booster?
(see Ken Blake's (Microsoft MVP) post for additional info and links)
http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/is-it-advisable-to-use-uniblue-registry-booster/b40f0fc8-442b-4352-b427-860c2c29091b
Uniblue Registry Booster Reviews
Don’t pay for software you don’t need — Part 2
(see Some Registry cleaners do more harm than good)
http://windowssecrets.com/top-story/dont-pay-for-software-you-dont-need-part-2/
AUMHA Discussion: Should I Use a Registry Cleaner?
http://aumha.net/viewtopic.php?t=28099
Uniblue Registry Booster Review
IMO, the below recent article from PCWorld.com is an excellent read:
Cleanup Utilities: Can They Speed Up Your PC?
http://www.pcworld.com/article/230447/cleanup_utilities_can_they_speed_up_your_pc.html
http://www.pcworld.com/article/230447-2/cleanup_utilities_can_they_speed_up_your_pc.html
Regards,