Best Free Registry Cleaners

Registry Repair is one of the safest Registry cleaning tools available in the market today. Its scanning engine is fast,thorough and safe.
Problems with the Windows registry are a common cause of Windows crashes and error messages.This cleaner tool allows you to fix your registry and optimize your PCs performance.With a few easy steps, you are able to find problems caused by invalid entries, references and links in the Windows registry and provides a list of the errors found, you can then choose to selectively repair each item or automatically repair them all.
Whenever you clean the Registry, a corresponding Undo file is generated for any changes made which can be used to recreate the entries deleted. You can restore any changes by clicking 'Restore previous repairs'. For added security,Registry Cleaner uses an 'ignore list' containing entries which when encountered upon while scanning are ignored.
* Invalid paths
* Invalid file associations
* Invalid file types
* Invalid custom controls
* Obsolete software entries
* Dead file extensions
* Invalid application paths
* Invalid help paths
* Invalid fonts
* Obsolete start menu order
* Adwares and Spywares that use registry
* Invalid startup programs
* Invalid shared programs
* and all other dead entries through out the registry.

Its fast and safe, only showing errors to be repaired/removed

Comodo System Cleaner is a powerful suite of utilities and tools that allows you to make your Windows XP or Vista computer faster, more efficient and more secure.
Take control by customizing virtually every aspect of Windows XP or Vista with just a few mouse clicks. Optimize system performance, disk space and overall stability with built in Registry Cleaner and Disk Cleaner tools Gain complete visibility and control over your computer's hardware, software, processes and performance with powerful diagnostics tools Ensure complete on-line and off-line privacy by clearing the history, cache and temp files of Internet browsers, instant messengers and Windows applications Protect your privacy and data with essential security utilities like Permanent File Wiper and built-in hash value checker and more... Available in 32 bit and 64 bit versions for XP and Vista and Windows 2003 server. Comodo System Cleaner is 100% free to home and business users.

This is fast, uses less resources, better registry cleaning, more of a tool for the experienced user

Advanced SystemCare Free (formerly Advanced WindowsCare Personal) has a one-click approach to help protect, repair, clean, and optimize your PC. With over 50 MILLION downloads since 2006, this fantastic, award-winning, free PC repair software is a "must-have" tool for your computer. 100% safe with no adware, spyware, or viruses; a PC maintenance program that’s incredibly easy to use.
Why waste money on expensive "registry cleaners" to fix your PC when Advanced SystemCare Free will repair, tune, and maintain it for you – for free!
Key Benefits

* Ultimate Speeding Up with New Added Turbo Boost
Advanced SystemCare is built with Turbo Boost to speed up PC by shutting down unnecessary background processes, cleaning RAM, and intensifying processor performance.
* View What Has Been Optimized
New version can let you view log files of what have been optimized in your system.
* Uninstall Unnecessary Application and Remove Leftover Files
Speed up PC by removing installed files and entries that were left on the system with built-in tool Advanced Uninstaller.
* Enjoy That New PC Feeling Again
Whatever version of Windows you’re running, enjoy that “good as new” speed usually only experienced on a brand new PC.
* Powerful Hard Drive Defragmentation
Fast, powerfully and incredibly effective Disk Defrag function to defragment hard drives - up to 10 times faster than other defragmentation tools.
* Next-generation Free Windows XP/Vista/7 Registry Cleaner and System Optimization
Safely cleans registry junks, compacts registry bloat and defragments the registry for blistering-fast performance.
* Defends PC Security with Extra Protection
Secure your PC – quickly and easily. Scans and removes spyware and adware using up-to-date definition files. Prevents spyware, hackers and hijackers from installing malicious items on your computer. Erases and updates your PC’s activity history with this powerful free XP registry cleaner. Security and Privacy assured!
* Quick and Extensive Clean-up for Hard Drives
Boosts your system’s performance with Advanced SystemCare Free, the powerful free XP registry cleaner by cleaning missing files, destroying unwanted files, deleting obsolete files, and removing junk files. Supports deep-cleansing of more than 50 types of junk files.
* Speeds Up PC Performance and Internet Access
Tunes up Windows by releasing the built-in power of your system. Dramatically improves both system and Internet performance by up to 400%.
* Fixes Multiple System Errors
More than a mere free XP registry cleaner – keeps your PC stably and running at peak efficiency.
* Extremely Easy to Use
Completes its work with just one click! Scans, repairs and secures your PC in one minute.
* Safe and Free
100% free with no spyware or adware! Advanced SystemCare Free is a safe and trusted PC protection and maintenance solution from a leading software vendor.

this is ideal if you like a 1 click automated service, cleans your disk, registry, removes junk, checks and removes spyware, can optimize your system automatically

Wise Registry Cleaner free is a powerful free registry cleaner and registry optimizer, it speeds up your PC by cleaning your Windows Registry. The PRO version help you improve your PC's performance by optimize your Registry, and it's so easy, you only need make a few clicks.
The Registry is at the heart of every Windows computer. The older your PC is, the more junked-up its Registry becomes. Badly written programs (and there are plenty of those around) don't bother to clean the Registry when you uninstall them, and some programs add unnecessary junk to the Registry. The more junked-up your Registry, the more likely it is to crash or to slow down your PC.
This freebie does a neat job of cleaning out the Registry junk. It scans the Registry, flagging orphaned or bad Registry entries, and shows you the name and values for each. It identifies Registry entries that may be dangerous to delete, and those that are safe to delete, so you can distinguish between the two. It also lets you decide which entries to delete, and which to keep. For safety's sake, it can also back up your Registry before a scan, so that you can restore it, if the program causes any problems.
Wise Registry Cleaner is one of the safest Registry cleaning tools available in the market today. Its scanning engine is thorough, safe and fast.

this one is slower than some of the others, it does use a little more resources than the others