Windows has been around since 2001, and the amount of information out there to repair Windows XP registry errors abounds. However, the amount of information that is useful is another story.

There's a reason that Windows XP is still the most widely used operating system worldwide, and that is because it is stable and reliable. Just like any computer, you may come across some potholes and hang-ups, but generally, you can fix most problems with a slow computer or an unresponsive program by using the built in features on the operating system like CheckDisk, System Restore, or Defragment.
The First Thing to Do When You Have an Unresponsive Program
Sometimes, you just can't get the program to do anything. It is just frozen in space and time and you need to shut it down. It is usually in your best interest to avoid pressing down on that power button for 20 seconds until everything reboots. This type of shutdown is harsh on your system and causes registry problems.
Continue read here
How to Repair Windows XP and Troubleshoot Stubborn Corrupt Registry Files