1. Click the "Start" menu button to open the Start menu.
2. Click "Run."
3. Type "regedit" into the text field and press "Enter."
4. Access the many different entries in your Windows XP registry. It is separated into primary sections: HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, HKEY_USERS and HKEY_CURRENT CONFIG. Each section contains a different set of entries related to different aspects of Windows XP operation.
5. Click on one of the plus-signs (+) next to one of the root directories, opening a more detailed list. This second level will have more directories to choose from, and will make it easier for you to find entries you need to clean the registry.
6. Delete entries in the registry that you know are either causing conflicts or are no longer necessary. Do this by pressing the "Delete" key, or by right-clicking on your mouse and choosing "Delete entry."
7. Invest in a third-party registry application to help you clean your Windows XP registry. Several programs are available that do the dirty work for you. Some even include backup capabilities to retrace their steps in the event of a critical error.
8. Clean your boot records by changing which programs load themselves at startup. Click through both the LOCAL_MACHINE and CURRENT_USER directories until you reach Software/Microsoft/Windows/Run and RunOnce. From here, you can clean out registry entries that are causing certain programs to run on startup.