

The Windows registry is a central repository (database) for storing configuration data, user settings and machine-dependent settings, and options for the operating system. Registry cleaners are extremely powerful applications that can damage the registry by using aggressive cleaning routines and cause your computer to become unbootable. In addition to Broni's link Bleeping Computer DOES NOT recommend the use of registry cleaners/optimizers for several reasons: I would recommend performing a repair installation of the operating system, since you used the registry cleaning portion of CCleaner.
