Free Registry Cleaners

CCleaner is the best free registry cleaner program I've tested. It's easy to use, prompts you backup the registry before it makes changes, and includes a number of other useful tools.

The CCleaner registry cleaner work on Windows 7, Vista, XP, Server 2008/2003, and older Windows versions like 2000, NT, ME and 98. 64-bit Windows versions are also supported.

Piriform provides both an installable and a portable version of CCleaner. I tested the CCleaner registry cleaner using their portable version in Windows Vista.

If you're set on using an automated tool to fix an issue you have that's caused by a registry problem, I highly recommend you use Piriform's CCleaner freeware registry cleaner tool.

Important: Be sure to download CCleaner from Piriform's site and nowhere else. There is at least one other program out there that's attempting to imitate CCleaner but then charge for the cleaning, so be careful.