Windows XP registry is a structured database that is a repository of all system, hardware, software, and user configuration stored on your system. Your Windows operating system and all other applications and programs installed on your system consult the registry in the background to perform each and every task. Information in the registry is stored in the form of values, each value has a name, and holds one of the many different types of data within it. A group of values are stored in a key, which is represented by folder icons in the registry tree. Each key can hold many subkeys within it thereby forming the hierarchal registry structure. To view the registry you need to run the regedit.exe file to open the Registry Editor window.
Registry Root Keys and Registry Hive
Registry comprises the following five root keys.
HKEY_CLASSES_ROOT (HKCR): Includes information related to file types and extensions, registered classes, and URL protocol prefixes. The information in this root key helps your system identify the course of action when you or some other application accesses a particular type of file. This key is the mirror of HKEY_LOCAL_MACHINE\SOFTWARE\Classes.
HKEY_CURRENT_USER (HKCU): Includes configuration information related to user currently logged on to the system. This key is actually a mirror of the information included in the HKEY_USERS—discussed later—and displays configuration information related to the current user.
HKEY_LOCAL_MACHINE (HKLM): Includes all configuration information related to hardware and software on your system.
HKEY_USERS (HKU): Includes user information that the HKCU key refers to display current user information. The .DEFAULT key in this key is used as a template to create new user profiles. The user information related to the current user is usually included in the S-x-x-xxxxxxxxxxx-xxxxxxxxxx-xxx key.
HKEY_CURRENT_CONFIG (HKCC): Includes hardware and software information related to the current user. Just like HKCU, this key is also contains information mirrored from the HKLM key.
Now that you know about the five root keys you will see that only HKLM and HKU are real root keys and the other three are just mirrors. For every branch in these two keys a separate hive file is stored in the C:\Windows\System32\config folder. New registry hives can be added or removed from these keys during the course of operation.
Registry Errors
There are many reasons that may lead to problems with the registry. When you uninstall programs and applications from your system, related registry entries are also deleted. However, at times, some registry keys may get left behind or may leave vacant spaces—registry holes—in the registry. Incorrect uninstall may cause errors related to shared DLLs, ActiveX and COM controls, incorrect file associations, and many more.
When you install an updated version of an application, the older files and registry entries may not be removed, increasing the number of obsolete and redundant entries in the registry. Additionally, if you are an avid internet user, then the chances of malicious software such as viruses, spyware, adware, and Trojans downloading on your system is high. These malicious software programs may also add incorrect entries to the registry.
Overtime, registry holes, obsolete and redundant entries, and other unnecessary information leads to unwarranted growth of the registry and can eventually cause severe damage to it. A damaged and corrupted registry may increase system errors and crashes and may even render your system unbootable.
Repair Registry Methods
To repair the registry, you need to scan the registry for errors and then delete the unnecessary and obsolete entries. You can perform manual registry repair by using the Registry Editor. However, the manual process is tedious and requires you to be very careful.
The best and easiest way to repair a registry full of errors is to download a registry cleaner software from the Internet. With a reliable registry cleaner software in hand, you become a pro at repairing all registry errors. In addition to removing unwanted registry entries, registry cleaners enable you to perform many other PC maintenance activities. Some of these activities include, managing Browser Help Objects (BHOs), managing privacy data, managing startup programs, removing orphan files, and defragmenting the registry. A good registry cleaner program not only helps you in maintaining the health of your registry, but also helps you enhance your computing experience.
The registry is a critical component of a Windows XP system. It includes five root keys HKCR, HKCU, HKLM, HKU, and HKCC, out of which only HKLM and HKU are real root keys and the other three are just mirrors. Whenever you run a code, browse the Internet, open a Word processor, or even resize an application window, information is added to or accessed from the registry. A lot of this information stays behind even if it is no longer required, leading to fragmentation and corruption of the registry. To repair the registry and restore your system to a healthy state, you can use a registry cleaner software. A registry cleaner software helps you easily scan the registry for errors and perform registry repair. You must also run regular antivirus scans on the system to keep your PC free from malicious software.