The Windows registry is a directory which stores settings and options for the operating system for Microsoft Windows versions. It contains information and settings for all the hardware, operating system software, most non-operating system software, users, preferences of the PC, etc. Whenever a user makes changes to Control Panel settings, file associations, system policies, or installed software, the changes are reflected and stored in the registry. The registry also provides a window into the operation of the kernel, exposing runtime information such as performance counters and currently active hardware. Read more at Wikipedia

The problem: need for registry fix

Some software and hardware developers use outdated or incorrect installation processes that fail to remove all references to the application or hardware when it is either installed or uninstalled.
Uninstalling or changing software, hardware and drivers never leaves a PC clean. Entries are left behind in the computer registry causing the PC to become unstable and corrupted. This results in sudden crashes, system failures and unknown error messages that ultimately cause a severe lag in the PC's performance.

When software or hardware is uninstalled it is highly probable that remnants are left behind on the hard drive or in the registry that clog up the system. Without a good program to remove and fix these entries there may be problems that cause imminent trouble including:
* Corrupted entries left in the Computer Registry
* Broken links and short cuts
* Program folders, help files, fonts and configuration files
* Applications that load when the PC starts-up
The PC quickly becomes bogged down, causing frustratingly slow performance with random errors messages and even system crashes.