CCleaner is a freeware system optimization, privacy and cleaning tool. 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. Additionally it contains a fully featured registry cleaner.
What's new in this version:
Version 3.19.1721 has added option to skip User Account Control (UAC) warning, support for Firefox 13.0 beta, and moved Thunderbird to be cleaned separately.