systems/registry cleaner?

Microsoft OneCare Live, (free) run “full service scan”

Updates windows, virus and spyware scan, disk cleanup, disk fragmentation (if needed), backup registry and then clean registry, and check for open firewall ports.

http://onecare.live.com/site/en-us/default.htm

http://www.saveintrash.com/regutility-best-registr...

RegUtility registry cleaner is a multi-award winning Windows best Registry Cleaner for Windows 7, XP, Vista.

Uses high performance detection algorithm to stop and repair registry errors. It identify and detect missing, corrupt and invalid items and error, Repair all errors, boost performance and provide stability for your windows system.

CCleaner is amazing and free.

It removes unused files from your system - allowing Windows to run faster and freeing up valuable hard disk space. It also cleans traces of your online activities such as your Internet history. But the best part is that it's fast (normally taking less than a second to run) and contains NO Spyware or Adware! :)

http://www.ccleaner.com/

There are some comparison and review of TOP 5 registry cleaners.

http://www.registry-cleaners.info/

You can download and scan your PC for free.