System registry performs critical functions and ensures smooth functioning of many operations. All Windows based computers have a registry which works behind the scenes and handles everything from updating user profiles to holding important information about the software that are run. After ruling out a virus infection, if the following symptoms crop up, it is most likely that you are encountering a Windows registry problem.

• PC slowdown
• Screen freezes while you are performing a task.
• Frequent crashes
• PC needs frequent rebooting
• unable to remove a program using add/remove dialog
• You are unable to open certain programs and can do so only after shutting down your PC and turning it on again.

Windows creates backup of your system registry as you boot your computer. A number of methods are used by the windows to restore the system registry.

• The system registry can be restored till the system is bootable. It can also be restored from the Windows recovery environment.
• The Recovery Console can also restore the information. Operating Systems based on Windows NT also creates the backup of the registry structure.
• Data of device driver and hardware can be restored by the Last Known Good Configuration option in case of Windows NT based systems.
• To scan and fix the system registry, Windows Me and Windows 98 have checker tool, which creates back up of the system registry by default.

Registry cleaner software helps you to clean up and repair your registry and fixes all registry related problems. A number of registry cleaners are available with different features. Some registry cleaners only perform error scans and then ask you to remove the error manually while some perform a proper scanning of errors and fix them as they are equipped with a fully automate tool.