To put it simply

Apart from just increasing the speed of the system, registry cleaners actually correct errors in the registry, there by ensuring that the user does not have to face the worst case scenario of an operating system reinstallation. That is why a majority of computer experts recommend installing programs that can gauge the health of your registry and safe guard yourself against future registry related problems. d) HKEY_CURRENT_CONFIG This essentially stores information that is collected every time the machine boots, and can vary from boot to boot. All versions of windows in use today have the windows registry as an integral part of the operating system. A basic overview of the structure of the windows registry in your operating system, can be seen by typing in regedit in the run box.
To put it simply, anything that is a part of windows leaves a small footprint in the windows registry. b) HKEY_CURRENT_USER Since windows allows multiple users to log on to the same machine, this key stores environmental settings of the user that is actively logged into the system. The windows registry is basically divided into hive keys or HKEY, the hives are then further divided into sub keys, and sub keys can have more sub keys and so on. Disaster PreventionAs mentioned earlier, that windows cannot function without a registry, even if the registry is intact but corrupted, there will be frequent system crashes, and sluggish speed. c) HKEY_LOCAL_MACHINE - This hive key stores the information of ALL the users in a computer. In a nutshell the windows registry keeps track of everything that the operating system uses in terms of software and hardware. The windows registry has information about the hardware, the programs installed, the various user settings and also essential information like file associations and system policies. The windows registry is the actually a database that stores the settings, and various options for the windows operating system. The biggest problem with a reinstallation of the operating system is not that it takes up time, but its the fact that sometimes there is very little hope for data recovery and months of work can be lost just because proper precautions were not taken to keep the operating system's registry in tact.
 There are some very good utilities like WinUtilities that can actually scan the registry for any problems or invalid entries, and fix the problems to improve the operating system's stability and performance. Based on the types of HKEY's the windows registry has the following hives (the names and number of HKEYs vary from operating system to operating system)a) HKEY_CLASSES_ROOT This stores vital information like file associations (which program opens which file) and the applications which are currently registered with the operating system. However before we discuss how a registry cleaner like WinUtilities helps, the first thing to discuss is the basic components of the windows registry.
One of the biggest problems with having a registry in windows is that, a missing or corrupt registry means windows cannot boot, it requires considerable amount of expertise to fix windows registry related problems, in fact the problem with windows is that it does Operating Room Stainless Steel Products Suppliers not always give you meaningful error messages, and more often than not it takes some skill just to diagnose an error as a registry related error. Registry cleaners, not only clean the registry but also back up the registry, so that registry can be restored in case of problems. Some of the basic functions of a registry cleaner are mentioned below. A corrupt or cluttered registry can be the cause of many computing problems from a slow operating system, to frequent systems crashes. Role of registry cleanersThe most popular reason for registry malfunction is not hardware failure; far from it, more often than not frequent installing and uninstalling of software actually clogs up the registry with pointless information, when unchecked this can lead to the registry failing all together, a scenario that can sometimes warrant a reinstallation of the operating system.