Please introduce me a good utility for cleaning Windows registry..

I’m currently having trouble with my windows registry. Please help. I’m in need of a free and reliable registry cleaner.

How do I restore the Internet Explorer Windows registry entry back to its original form? I downloaded some software by accident that was obviously malware from a video site. Now the IE reg setting changed!

Yahoo toolbar was installed on workstaions on our LAN. After uninstalling the program I find that windows registry was modified and client downloads are blocked. How do I reset registry?

Hi
I’m looking for a good software that can defrag hard discs and windows registry without risk.

Thanks